I recently saw a rehab in Federal Hill for $299,000 (on Patapsco Street by Cross St Market). Locust Point is going to be even cheaper than that. And the Riverside Park area is good, too (just don't let them convice you that it is Federal Hill...).
I've been keeping my eyes open-seems like things are slowing down in Baltimore (as everywhere else). I think if you look hard enough, you shouln't have a problem finding a good property for $275,000. Some homeowners/ developers are unrealistic in their asking prices. Make an offer-you never know what might be accepted...