I'm curious, what's the market like for custom spaceship design and 3D modeling art these days? Any idea about pricing?
None, sorry.
I was lucky enough for a fan who also played the same games as I did, to offer to do a cover for me, after I asked in the game forums if anyone could send me some combat game images. (I have permission to use them from the game makers.)
It all went from there, and he's refused all attempts from me to get him to accept anything for all the work he put in.
He even buys each new book of mine himself, when I'd be happy to drop a copy on his Kindle for nothing.
So, no, no idea what getting a model made actually costs.
But.... being able to use unique ships on your covers, is worth spending some money over. In the same way some authors do model photo shoots to get their unique covers. Probably similar costs involved.