Food, Water, and Cost of LivingIt costs $150 a week to live at the Inn in town. That's 1/4 the monthly cost of living for Status 0 characters, so that's defensible. But delvers are living on the road - they should be paying 20% of the Status -1 cost of living every day, for $420/week. Smart delvers know that they can buy a week's worth of food for $63, so it's hard to justify $360/week just to put a roof over their head.
Basically, the cost of living stuff is entirely too cheap. This has several negative consequences. Because it's so easy to make enough to live for a week (5 delvers need to earn $750, which is less than $2400 in raw goods at the usual 40% discount - or roughly 5 generic humanoids with leather armor, axes, and shields), the various rules for "failing to earn enough to support yourself" are wasted text. Similarly, the use of skills like Survival to cut the cost of expenses is pretty much wasted, because while an extra $75-150/week is appreciated, it's not really all that much. And the GM can hardly even give food as treasure, because at $4/lb in value, food has a worse value/weight ratio than axes or other weapons that no one bothers to take as loot unless they're desperate.
I really recommend tripling the cost of living, to $450 or $500/week, and raising the price of rations to around $10/meal. Survival oriented delvers get more benefit for their skills, earning enough to stay in town is a large enough problem that PCs are forced to take risks for the big scores, the GM can meaningful give out treasure like food or deeds to houses in Town that reduce the cost of living, and heck, even buying a house becomes a sane investment.
Another problem with the current cheap cost of living is that it necessarily means that using in town skills to raise cash can't produce much cash. A bard with Urban Survival needs to raise $75/week by busking, and then he can stay in Town forever. Which is boring, so the rules make it difficult for even a bard to busk for survival. But since busking can barely produce $70/week, it can't buy anything else that a delver wants either, except for maybe a very beginning delver who needs that one last pouch or something. Tripling the cost of living and the rewards of street performance makes it so the bard still needs to go out and adventure, but $200+ week in busking income while searching for rumors is enough that the bard can buy a potion or some alchemical fire.
Abundant LightIt's clear from the published resources - Instant Load-outs, the existence of helmet- and shield-lanterns, the prechosen gear for the rival delvers in Mirror of the Fire Demon - that managing light sources is supposed to be a consideration in DF. It's also clear that the existence of cheap, long-lasting, and hands-free glow vials means that it doesn't require much consideration. People can either buy expensive, heavy, and short-lived torches and muck about with arguing which sucker needs to give up his shield or two-handed weapon to be a target, and then everyone can huddle around the sucker. Or the delvers can each buy a glow vial and forget about it. (Oddly, later editions of D&D had a similar mechanic with torches versus sunrods). That's before we get into wizards and clerics with Continual Light spells.
My only vague solution to this is to radically up the price of glow vials (to $150+ each) and to thread my delves liberally with no-mana and no-sanctity zones. Or to just accept that accounting for light is boring and assess the minor glow vial tax.
Potions and Poisons
Poisons and potions are probably too expensive for what they do. A good poison that can reliably damage an enemy - assuming you can get past the enemy defense and penetrate armor - costs as much as a sword. 4 doses cost as much as fine sword. And a fine sword will penetrate more armor and do its bonus damage against foes more than 4 times. Smart delvers sell poisons, they don't buy them or use them."Woe! I'm being killed by treasure!" -- Bruno, as her pixie got caught in a trap that dropped potions on her head.
Similarly, potions are crazy expensive. A Flight potion costs several thousand - nearly as much as a suit of plate armor. That's for a one-time use of flight. It's cheaper to get the party wizard to cast flight and just keep feeding him Paut potions.
Reducing the cost of poisons and potions by a factor of 3 to 5 makes them affordable, expendable items. They're still light enough to make good treasure, though.
Horses, Mules, and DonkeysI've tried running some far-reaching exploration games, the kind of things where the PCs need to head out for 2-3 weeks just to get to the dungeon. You'd think that'd be the kind of situation where the delvers would want horses, but between the upfront cost ($1500+ for an equipped riding horse, $5000+ for a war horse) and the recurring expenses (easily $15/day for feed and the need to hire a guard to watch them while the delvers are in the dungeon) and the fact that really, standard GURPS horses just don't carry that much, there was never enough value in the horse to make up for the costs.
This is depressing as a player, too. After striking it rich in the dungeon and getting a few thousand $ to spend, it's natural to think "my delver doesn't want to walk in the mud anymore, I should get a horse." But if that horse is 75%+ of available wealth, and the decision is to get a horse or to get a slightly improved weapon or armor - it's easy to see which way that one goes.
Dropping horse prices by a factor of 3 or 5 again helps. A knight can afford to shell out $1000 on a heavy warhorse that'll only help in random encounters on the way to the dungeon. Everyone else doesn't mind spending a few hundred on horses that will speed travel enough to reduce the number of random encounters. It even becomes not insane to hire grooms for the horses, mount them on horses, and hire donkeys and mules to provide the feed for this cavalry troop.
Magical EnchantmentsThe pricing for magical items is insane. Cornucopia quivers are as cheap as 50 arrows, but provide much more than 50 arrows - so every Scout ends up buying a bodkin Cornucopia, an impaling Cornucopia, a willowleaf Cornucopia, and a blunt Cornucopia quiver for less than 1CP of funds and never runs out of ammo EVER. Tracking ammunition expenditure is a hassle, but I'd rather that getting the "Bow of Endless Ammo" be an exciting adventure reward, rather than something that happened during character creation.
Similarly, the Lighten 25% and Lighten 50% enchantments are very cheap, compared to the 10x cost of Fine armor. Lighten 25% basically comes free with every armor, while its more cost-effective to get Lighten 50% put on any armor that has a base cost of more than $1000. It's depressing to describe a suit of fine field plate and realize that in the PCs' eyes, it's vendor trash.
Continual Light enchantments cost $8000+, the value of 300 glow vials - more than the PCs will probably ever use in a campaign. Alternately, the wizard or priest can just cast Continual Light on the weapon every week or so, at a cost of basically free.
I don't know that there's a good solution, short of going through GURPS Magic and repricing everything. As a first pass, Quick & Dirty enchantments just have to go. Lighten 25% for $2000 is still a really good deal, but at least it's no longer a no-brainer and there might be a period where the delvers aren't all wandering in magically fortified and lightened armor.
+Nathan Joy, the GM in my online game, has a house rule that only items with +1 or more in CF modifiers can be enchanted. It helps some with armor (though I think everyone just got Ornate +1 armor and moved on) but it's just not enough.