There are lots of beer retailers in Baltimore City, but as is the case in most of this country, only a few of them know beer and cater to the demands of more educated beer consumers. This is a tough area for me to know about since I stick to the stores I know sell good beer. Good range of microbrewery and import products. All of the local microbrews, Anchor, Sierra Nevada, and quite a few good English ales.
Prices are reasonable.
Excellent selection of wines as well. Mis-treated bottles of beer always a possibility here since most of the better beers are on exposed shelves under fluorescent lighting. Can be good, but know what you're looking for. Many seldom-found products from the west coast and Europe. Count on finding a lot of California micros, including Anderson Valley, Mendocino, etc.