Yeah, no problem, though there is one factor to bear in mind: I still almost exclusively use 3D models, and while my collection is pretty extensive (about 16 gigs fully compressed, which is somewhere in the region of 6,000 models covering an awful lot of topics) there are gaps in it. No great big gaping ones but in the unlikely event that you wanted to involve a hand held grenade launcher in an image then it might be a problem.
So, if you were looking for something that I didn't have already I can possibly make it myself but it takes longer. The other alternative is that I can go out and buy the item in question if it's easily available.
As far as I'm concerned, unless I had to buy a model I wouldn't be too worried about taking cash for it since it all looks good in a portfolio. If I had to buy the model then I'd probably be asking for the cost. If I had to make the model then that's no trouble since I can always sell it.