You don't have to overspend, by any means. Get some cheap board shorts and I'm sure you have some sports tshirts you can wear. They will be a lot better than yoga tank tops and whatnot.
Mouthguard - yes, 16oz gloves - yes, shin guards and head gear (if you're doing full contact sparring)- yes, gi - yes. That's pretty much all you need. I'm not sure about the groin guarding with girls. Does it hurt a lot for a chick to get hit in the moo moo? I have no idea. If it hurts getting hit there or having an elbow jabbing in there during submissions, get a vag cap aswell. Oh, and good titty support if you have big boobs.
NYBA Champ @ 170!