I thought I had read on here that the cost of an Accessible Bedroom with a disability fare was based on the current cost of a Roomette. But on several days in April, an Accessible Bedroom on the northbound Star is more costly than a full-fare Roomette. I called Amtrak, and the agent said the fare is based on availability, and has nothing to do with Roomette fare. So ... it seems the only way to find a low Accessible Bedroom fare is to go on the website and check every possible date (and it requires going thru the "type of disability" screen for each date), making a list of the fares by hand. Amsnag is of no use, other than to give a general idea of how full the sleepers are. It's a real pain in the something.