When you say "walking distance to the action" are you referring to a certain theme park or nightlife? It helps you are more specific about where you want to visit - WDW, Universal, ect?
There are tons of hotels on International drive which is a fairly central location to all the theme parks and is right in the thick of restaurants, ect. You can walk to a lot of locations from I Drive, plus there is a bus that goes along the entire route.
As far as traveling to the theme parks, many hotels do provide shuttles, but they are not the most efficient in terms of getting there quickly.
There are a lot of budget hotels along Irlo Bronson Blvd, which is closest to WDW. You can walk to restaurants and stores, but I'm not so sure about nightlife.
It's basically impossible to walk to any theme parks from hotel locations. The only exception to that would be hotels in the Downtown Disney area. From those hotels you could walk directly to DTD and then take the Disney transportation to the parks via the ticket & transportation center or the resort hotels. The hotels in the DTD area tend to be less budget friendly then what you might be looking for.
Do not rent a car a try to sleep in it. That sounds dangerous and not conducive to a good vacation.
I know someone who recently rented a hotel along Irlo Bronson Blvd for $33 a night.
Try this
This individual rented a compact car. Consider checking carentalsavers. com for car prices. You could hit on a good deal. Remember - if you don't have a car you are going to pay for transfers from the airport.
Hope this helps.