Asking for money

What is the best way to ask for money in an invitation? My fiance and I already have most of our house things from the house warming party we had when we first moved into our apartment. Our children (thankfully) have not broken anything so we dont really need anything like a coffee pot or something else like that. So we have decided on a wishing well wedding but are not sure of the proper way to word it into our invites. Is there a proper way?