Delilah's can be a great deal; I've been to several of these and hosted a few myself. Prices and deals seem to be sort of negotiable, but it's usually something like $10-$15/person for two hours of draft beer and "wine," which no one ever drinks. You get the whole upstairs to yourself for this period, with a bartender, who'll be happy to make anyone else anything else they want to drink for normal prices. Pretty sure they have Bass, Guinness, Stella, Hoegaarden, at least one Goose Island, and a couple of other decent things.
They have a tendency to double-book the upstairs, so be aware of that. But there's no deposit, and they won't hold you too strictly to a minimum number of guests.