No it's not a bad taste. It is up to your will and taste. If you want to put up a money tree, you should not bother about anyone comments.
Should You Have A Money Tree At A Sweet 16 Birthday?
Shoot, I don't see anything wrong with it...it's your birthday, and your sweet 16 at that! If someone wants to donate to your sweet 16 fund, let them...if not, that's their decision. No harm done...