Sounds like there isn't much else you can do then. If she refuses to compromise then you have to decide what you want. If you have the money, then offer to pay half and at least get a few pictures of the outfits of your choice. If you don't have the money, then it's either chose to have a bad outfit or no pictures. It sucks she won't work with you on this. Good luck OP
I've told ya before and I'll say it a million times but you seriously need to move out!!! Lol
If you don't want the type of outfit she wants then just tell her no thanks on the pics. Especially since she won't compromise even a little where you BOTH like the outfit. Makes me grateful...my mom alway helps pay for pics and if inlaws want some thy have to buy their own, but I ALWAYS pick out his outfit(s)!!!