Firstly, I say grow your hair out a bit, a lot of teenage boys have longer hair and but clip in hair extensions, they look so much better than wigs ever do.
They're also cheaper.
I grew my hair out a bit, used extensions until my hair was long enough to style it.
Now is your friend female? if so, just put a few dollars away weekly and go shopping with her.
Go to op shops (second hand shops) and buy from there, building a wardrobe will cost a fair bit.
as for unsupportive parents, cannot help you there