If you had maybe done something on your own, meshes say some fan art in a way. But really you haven't even done that. The models you are using are freely available for download on 3D printing sites for people's own uses and enjoyment and not to sell as your creations in a virtual world. That is besides the blatant copyright infringement of course.
And in that mesh upload quiz that we used to have to do to be able to upload meshes at all it does quite clearly state that if it looks like something that is under copyright, even with changes, then don't do it. It is pretty simple. And the fact that there are some other things on the MP that fall under this is due to them maybe not having been discovered or reported.
Your question was however for an investment into your business. To pay a mesher and so on. (Free models of a 3D printing site... ) and my advise was to rethink and legitimise your business model before you seek partners. So whatever your reasons are that you think what you are doing is ok, I don't think you will find someone to go into business with like that.
If vinyl figures are your passion, make your own. Be creative and use your imagination.