some items are very expensive when trading, to an absurd degree. Aside from lavish meals (cave crocodile egg roasts and similar can reach values well above 20.000 dorfbucks) most glass items are expensive, which is ridiculous since glass, if you have sand, is almost as easy to make as the wooden stuff. Try making glass serrated discs. The game is still under development and some things, like these, are unbalanced. Maybe once the economy gets reworked it'll change. For now, I just don't intentionally produce those goods just for trading.
At least glass crafts require some sort of infrastructure: you need to make (or buy) bags (=tails+farmer's workshop+loom+clothier), then collect sand at the glassmaker, then acquire fuel (=wood+smelter), then make the craft.
So, starting from nothing but an axe and some stone, making a single wood ball requires 3 jobs (chop wood, build carpenter, build ball). Making the first glass craft requires (plant pigtail, harvest pig tail, build workshop, process plants, build loom, weave thread, build clothier, make bag, build glassmaker, collect sand, chop wood, build smelter, make charcoal, make craft)=14 jobs. Even if you start with 5 bags (the default), it still requires 6 jobs, and it is more difficult to manage since those bags will be stolen to store seeds if you don't pay attention, and you need to juggle collect sand and make craft jobs. So, it makes sense that glass crafts are more expensive than wooden balls.
(If I were to design the economy, I would use the number of jobs, amount of infrastructure, and scarcity of ingredients as the determiners of value, e.g. every simple wood product made by a dabbling carpenter should have approximately the same value, say 9 for 1 (wood) + 3 (1 building) + 5 (1 job). Quality modifiers should depend on the product, eg a masterwork wooden pipe would by only slightly more expensive than a normal pipe (who needs masterfully crafted pipe?) but for more sophisticated goods such as weapons (utility increases with quality) or crafts/food (happiness boost increases with value) the difference is higher. For example, maybe a pipe or block as x1 for normal and x3 for masterwork, while a craft has .5 for normal and x10 for masterwork. That way, a beginning fortress would be best off selling raw ingredients and simple commodities, while a more mature fortress with a more sophisticated industry would sell crafts and other finished goods)
[and don't get me started on the stack multiplier in roasts. 5 leaves x 5 leaves x 5 leaves should yield 5 roasts, not 125 :-) ]