I think it would be nice to be able to build a contract for a specific item for specific materials.
Case in point I am making big shovels on my server for other players, now I want to be able to get the raw materials back for them so that I can make more. So at current efficiency I would need 8 iron ore and 22 logs but when i set it in the store people seem to just bring me the logs to buy the big shovel as it is much easier for them. By this happening I am not getting back the iron ore I need to make another shovel.
The contracts right now only work with paying someone with currency, but I would much rather have one that says bring me 8 Iron ore and 22 logs and you get a big shovel.
For a quick solution make a big sign infront of your store stating this, and also you can make it not worth the time to get too much logs,
for example, you need lots of iron ore atm cause of the balancing, throw a price on the big shovel of 999 and make the iron be worth 100 and logs worth 5 each that way you get approx 9 iron ore for 1 transaction of 8 and 22 :)