your price range is. For non-wheelchair visitors we often refer them to priceline bidding, but that won't work if you need disability access as there would be no guarantees.
Many of the the budget hotels on this list
http://www.accessnca.com/

are pretty funky.
The exceptions are
Cow Hollow Motor Inn in the marina
Hotel Whitcomb - downtown
which are both OK
The hostels are both OK but the Ft Mason one is a ways away form anything and books up way in advance.

Expect to pay more like $125 for a decent hotel w/ accessibility.