I don't think anyone's arguing he's going to get a huge payday by NFL standards. The argument is whether he gets starter money or not.
Yea,
he doesn't really have the leverage to ask for a huge deal after getting hurt in 2011, not playing much in 2012, and clashing with the coaching staff. There will be teams out there who want him. And sooner or later, his asking price will drop to the point where someone is willing to meet it.
Some of the obvious potential destinations:
Miami
New York Jets
Steelers
Colts
Broncos
Raiders
Lions
Packers
Falcons
Cardinals
Rams
Most of those teams have some degree of need for a RB, and not all of them will end up drafting one high. When the game of musical chairs ends, it's likely that Mendenhall ends up on one of these teams, IMO. And I think he'd have a good chance to emerge right away in any of these spots.