If it was family I would do everything I could to help ... I catered my brother's wedding (aghh still have canape nightmares!) We held the reception here in the sitting room, in the studio and in the garden and from memory had something like 80 people ... but i'd do it again in a heartbeat for family - for friends, well me and my big mouth I'd offer to  do something - but pay money - mm maybe not ...... give money instead of a present - ok - i guess youngsters do that a lot now - but not pay to go to a wedding so to speak ... and £500 ... in their dreams lolol