What to do about the birthday party?

OK, this is one of those dramatic friends not invited poor me kinds of things that I hate. But yeah. Okay, so I have three friends, Sue, Mary, and Ann. Sue is throwing a birthday party, and she invited me and Mary. She's really good friends with Ann, but her parents hate her (Ann, not Sue) and won't let her invite Ann to the party. Because of this, Sue really doesn't want Ann to find out about the party. So for Sue's present, Mary and I are pooling our money to buy her a Toyota (not really, but I think you get my gist). Ann knows about this, but she thinks we're just giving it to her at school. She wants to put her money into the pool, so we can get her a Porsche or something. She thinks we should all give it to her at school, but then how will Mary and I give it to her at the party? Rewrap it and tell her to act surprised??