For the direct-to-dvd/overseas market, you set aside 50-100k for a name, with the promise of a two week shoot, and they accept because the money to time commitment ratio is so promising. There are some people that say yes because they have nothing better to do, and others that just don't like to turn down paying work. Danny Trejo, obviously. Another director said Danny Glover won't turn down much if the time commitment isn't too bad and the pay is okay. Although he will half-ass the hell out of it, understandably.

He also said that it helps if you can film somewhere vacation-ish and make it seem like a working vacation.

Sounds like the one "name" actor these movies secure is by far the biggest expense associated with the production. Spend your money on providing a good experience for the star that you need on the dvd cover to create at least some glimmer of recognition at Red Box, etc., then do everything else on a shoestring, no frills budget.