If you demand walkable, then yes, you are up a creek. The only way to get purely walkable, with your grocer, theater, and night club all within a fifteen minute stroll, is high-density which generally happens in the heart of large cities, and is indeed expensive.
But how about bicycle-able? My town is about 5 miles square, very bike-able, and I was able to buy a townhouse at twenty-five.
Lots of newer suburbs are being designed with high walkability in mind.
My newish suburb is walkable to a movie theater, bike store, huge gym, swimming pools, Tae Kwon Do school, a couple hair salons and a barber, a full grocery, a couple clothing stores, about a dozen restaurants from fast food to high-end dining, a UPS store, an optometrist, a toy store, a ballet school, two coffee shops, a dry cleaners, a bank, a liquor store, weekly farmer's market about 3 or 4 miles of landscaped parks, about 20 miles of trail and just on the edge of walkability is a full 18 hole pro-level golf course.
They're planning on adding more stuff to it as well including a full county library and some other odds and ends.
There's a nicer development similar to mine about a 15 minute drive that offers a similar environment.
My friends live in an older neighborhood that's also just a 5 minute walk from a lively older "main street" style commercial area and likewise get all their shopping and such done that way. They live in a brand new house, but the town is a couple hundred years old and historic.
You have to hunt around for them a little, but they're definitely out there.
Off the top of my head: Chicago, Portland and Philadelphia are all fairly inexpensive with good transit.
If you're willing to pay a bit more: Seattle, DC, Boston, NY outside of Brooklyn and Manhattan, the unfashionable parts of LA.
If you're willing to live in the city center or put up with infrequent buses, Minneapolis, Louisville, St. Louis, Austin and Atlanta are all possibilities.
