Perk balance: Fine for buying. Prices go like (these numbers are an approximation) 100,90,80,70,60,50, which is reasonable, but super duper crazy OP for selling Prices go 10,20,30,40,50,60; each level multiplying the no-perk sale price.
In general, there is too much of a discrepancy between the prices of items with and without quality levels. Once you can craft level >3 stuff, almost nothing without a quality level is worth considering for profitability.
The trader is selling raw meat too cheaply. 2 per unit or something, almost free compared to other food ingredients.
Some common supplies like food or cement are sold in too large quantities, removing the challenge in this area. Prices are good though.
Some more specific items are too rare. It's not fun to have to go all around the map to visit all traders each day, hoping for bullets or a tool and die set.