Anywhere downtown is expensive, although try travelzoo for specials.  Outlying chains shave off a lot of cash.  If u r there for just a few days without a car stay along the MARTA line, eg Buckhead or Downtown Atlanta.  Cheaper hotels can shunt you to the MARTA line, but that is a pain.  If driving, be careful!  Especially on the interstates thru town.

A cheap option to stay in Downtown is Motel 6 Atlanta Downtown. I went there this summer, booked 1 week prior to my arrival and I paid something like 50-60$ a night.

I thought it was great to find a motel that's in heart of downtown, next to the Marriott.

It's a quick walk from all downtown attractions and not too far from Midtown.

Again it's a motel so it all depends on what kind of accomodation you'd like.

The Garden Plaza Atlanta / Norcross is clean and decently priced. The Savannah Suites on Pine st is another cool budget spot. For a little more money, I'd stay at the The Highland Inn. Small place that feels more like an apartment building has a southern feel to it.

Depends where you're staying/which city- area & what you plan to do in atl. But try Hotwire.com or hotels.com for cheaper last minute hotel rates. Just don't stay in areas like college park etc. Not safe!