regarding commissions:
few experienced vendors are going to make an entire quality conforming outfit, character/textures, set, etc for a couple hundred bucks.  quality work takes time, and even if you only pay them minimum wage its still going to add up. unfortunately this puts quality commissions out of the reach of most hobbyists.

but i can suggest two 'business models' that could potentially work out well for all involved:

1. get some people together and do a group commission. start a thread on it in the wishing well and drum up support, get others to donate, and you can raise a lot more money for a commission than otherwise. a mere twenty interested people contributing $25 is already $500. a thread where you are offering a fixed amount of cash for a certain product is going to get a more serious response than 'oh, i wish someone would make blahblah for poser'.

2. do a 'partial commission'. by this i mean that you are not demanding full exclusive rights to the final product, and afterwards the vendor can put it in their own store and sell it. so you are paying a fee to basically 'hijack' a vendor's direction. you get what you want made, you get creative input, and you get it before anyone else.... but once its done, the vendor can then put it in their store to recover the rest of its development costs. many vendors would be open to this type of arrangement, but again the less marketable a product is the more incentive youll likely have to give them.