Thanks for the advice.There are free programs i used to work with (or fairly cheap ones)
Blender for example and Milkshape 3d. I made Weapon Models for Counter-Strike/HalfLife Mods. It depends alot on how much detail you want, and how good your skinner is or how good you are yourself with texture making. The backrounds themselves could be made with [insert that program that generates scenic backdrops unfortunatly i forgot the name] combine the model with the backround via GIMP and you got yourself a backdrop.
I think all that together could be made with Poser but that costs a bit if i remember right, and you have to buy the models, not sure what they are actually made with