Invitation help ?!?!

So I live really far away from all my family (parents, aunts, uncles, cousins). I don't have any family or many friends in the area. I may do a Co-ed baby-Q just for the few friends and co workers around here but my mom wants to have a shower for me while I'm visiting my home town next month. I have to fly cross country there (by myself) and don't want to take extra suitcases. I'm going to do an online registry for Amazon so I believe people can get stuff off there and ship it to me directly. I'm just wondering how to say on the invite to buy from the registry and ship to me or give gift cards/cash, without it seeming rude ?!?