i always take a $16 faux-python bag with chain straps from Forever 21 when i go to the bars around here. it's actually rather nice looking (the faux python is surprisingly detailed), it snaps shut with one interior picket, it fits over my shoulder, and is just big enough for cell phone, cards, some cash, a lip gloss, and my keys.
i also have a red patent leather clutch from target that's a little larger. i'd say look someplace like that, it always makes me so nervous to take anything that cost more than $20 for a night out. that way, if i sit it in a puddle of alcohol on a bar (quite common in a town that practically runs on drinks that you have to DROP a shot glass in to - jaeger bomb, anyone?) then, hey, who cares?