I recommend getting something with wide range gearing (esp. very low gearing) - triple crank with alpine (aka MTB) rear derailer and cassette. You may think you can't ride up those hills, and maybe you can't now, but with a little fitness gain and the right gearing, I'll bet that you can. The least expensive bikes that come with very low gearing are mountain bikes - they often have 42-32-22 cranks and 11-34 cassettes. Some cross and comfort bikes are also geared really low but not all.