Interesting thread, I'd like specialized traders, and a bit variance to pricing (the biome related realism sounds neat). Plenty of other interesting ideas as well.
But overall, I find this thread difficult to answer with the rest of the game balance being so strongly up in the air.
Should there be gating items between playstyles or not? If there should, what are they? As it is, everything is being given with a mild inconvenience.
1.) Support all play styles, so non crafters can get what they need.
Personally, in a current SP game I'm trying to play a non-crafter looter with an archery/pistols build. Buying Concrete Mix and Cobblestone for an AI-cheese shooting range (horde base) has worked for the first three weeks. Once the AI is fixed.. no idea. Spent 3/5 points in Barter, so my sell/buy ratio is now about 3.5:1. Built a forge for iron arrowheads. Spent the points to build a minibike. So, three weeks in, I'm actually just a few skillpoints away from becoming a crafter, while stubbornly refusing to buy the points. Now that I think of it, a lot of my money has been made by selling Iron Reinforced Clubs to each trader, they sell for a good bit for 100 Iron, which isn't really a feature of a looter..
Nothing that I'm "sorely missing", but I'm having hard time not spending the couple of points for a cement mixer.
2.) Make it possible to make a living role playing.
To think about this, the first thing I'd need to ask, "What are the intented harvesting mechanics?". For the moment, we get the "destruction bonus" from resource nodes that doubles the yield of the node. I seem to rememeber that it is a bug. Are we getting double the resources we should?
Lumberjack selling 3 stacks of wood per trader reset, that is 6000 wood per day, no Better Barter? He'll get about 75 dukes per 1000 with your .2 => .15 barter change, so, thats 450 a stack. With luck, 450 a day. That's six cans from a vending machine, or three "stew types". Assuming the trader resets all the wood every reset (he won't, but you can rotate living around several traders to compensate), a lumberjack might feed himself. Is that "making a living"?
3.) Perk balance. Are the trading perks too good? I typically get by without them so maybe they are OP?
Given that you in this thread nerfed unskilled bartering by 25%, I guess it was OP in general

I ran some numbers to think about the effect of the change:
Oil, "EconomicValue=100"
In 17.1 B9, through the ranks of barter 0..5
Oil sells for: 20, 30, 40, 50, 60, 70
Oil buys for: 200, 190, 180. 170, 160, 150
Giving trading ratios ("how many items I need to sell to buy one"):
10, 6.3, 4.5, 3.4, 2.7, 2.1
Your new ratios will be (buy_markup=2, sell_markdown=0.15, Bartering value="0.05,0.1,0.15,0.2,0.25")
Code:
Sell: 15, 20, 25, 30, 35, 40
Buy: 200, 195, 190. 185, 180, 175
Ratio:13.33, 9.75, 7.6, 6.2, 5.1, 4.375
I guess that's not terrible. Poor lumberjack though
Some things to check, if you didn't already,
- Cigar, Barter value is now worthy of two skill levels in barter (maybe acceptable?)
- Grandpa's Awesome Sauce, Barter value
- Old Treasure Map, loot ratios between coins and other valuables (or just leave the coin box twice as valuable as the rest..? )
- Maybe Zombie Loot bag coin value balancing as well
Another thing that will still make the crafter the master of coin, Quality level affecting prices as much as it does. As in quality_mod="0.4,8"
Barter requiring int, a crafter at int 8 + nerdy glasses will make flawless items, at that 8 value.
Leather armor (with your newly modified ratios): a duct tape (43 buy at 5/5) 7 leather (269 buy), 312 total. Craft into Q6 leather armor, sells for 960, profit 650 per duct tape, (x15 items of armor) no use for the leather anyway
Flawless Iron Clubs sell pretty well still. 1120 for 100 iron (100 iron buyable at 170 coins, net gain for showing up at the trader, 950x3 = 2850)