If it can be done for a Bar Mitzva why can't it be done for a wedding?
The labor alone should make this a losing proposition -
Photographer - $1,000 (including photo touch ups and digital photos)
OMB - $800
Waiters - 5 x 20 per hour x 5 hours = 500
Kitchen/cleaning staff for event - 4 x 15 per hour x 5 hours = 300 + chef @ 200 per diem = 500
Hall manager - $200 per diem
Total 3000. That leaves 1500 for food costs (including prep), flowers, and overhead.
Even if you cut a couple hundred off of this, it's not profitable. Either there has to be a donor here, or all these people are hurting so much, they're willing to do events on the cheap to just get something.