You are not off base! One of the major appeals of a DW for me was the reduction in costs. $30,000 for one night of food seems absolutely rediculous for me. Food is one part of a wedding, you haven't even gotten a dress, paid a photographer, bought a cake, etc. I don't know who is paying, but if it is your parents, think about what else that money could go to.
There is nothing wrong spending a large amount of money on your wedding, it is a once in a life time event after all! However, if I (or my parents) had that kind of money, I would much rather put it towards a new house, car, or even school bills.