Try Electra bicycles, they have a few 'Townie' models with step-thru frames and deuralliers that'll help on hills and with heavy loads. Soem have disc brakes, others more traditional rim brakes, and maybe a single-speed model (or two). The electric models are over $1000, but the pedal-drive-only are below that (about $750).

Also look on your local Craigslist for a used one (step-thru frames are not popular in my area so they get discounted). If you're handy with tools and don't mind a little wrenching there are plenty of old Schwinn bicycles with step-through frames you can get cheap on Craigslist, too.