Just in the last couple of years, various bike manufacturers have started addressing this market. Trek's Belleville and the REI Novara Fusion both have dynamo LED combinations.

You may be able to order the REI bike online. I'd suggest you go check it out at one of their stores near Philly, or phone around to the local bike shops (LBS) to see who has a Trek or something similar.

Unfortunately, you need to forget going to a "big sports shop" and getting a good bike. With the exception of REI, sports shops in the U.S. will have a few basketballs, footballs, and volleyballs; a huge selection of golf clubs; some clothes for people participating in sports; and half the store will be dedicated to branded shirts, jerseys, and caps for local pro and college teams. If they have any bicycles at all, they're probably cheap, poorly made, and limited selection of Bicycle Shaped Objects.