I agree with Stealth. I guess I'm a bit of a capitalist, in that regard. Though, I have had a similar occurrence happen to me.
A person bought a custom set of Mandalorian armor from me, as most usually do. However, not long after, I saw that they used it to create a number of vac-form pulls and began selling them for twice what I charged them... Needless to say, I was a little fumed. That was the last set of custom work I did.
Between that and people going through the entire order process (about two weeks of work) and then agreeing but not paying... Yeah, I do feel your pain, brother.
If you charge for the files, you will weed out the majority of the I.D.10-Ts. Not to mention, it will give you some light compensation that you can turn around for a larger costuming budget.
But, that's just my opinion... I could be wrong.