Do yourselves and all of us a favor, and put your requests here, so that we don't have a bazillion threads all asking the same questions. I see we've already had 3 or 4 threads devoted to this.
To kick things off:
If you want cheap food that's decent, hit up Tin Fish or Ciro's Pizzeria. Ciro's has a special - two slices and soda for $6. That's some of the cheapest grub near the Con, and their pizza is good.
If you want stuff that's more in the moderate ($10-20) range, try Royal Thai, Bandar, Chopahn, or Alambres.
$15-20ish: Trattoria Mare e Monte, Cafe Chloe, Gaslamp Strip Club.