I don't know how many of those there are. But if there's not somebody better than Demint in a primary, then like I said, pickins would have to be pretty slim.
Even on fiscal issues he could be improved on. There were 17 Republicans who voted against all 5 bailouts and stimulus packages in 2008-2009, and they were all in the House, not a single one in the Senate, including Demint. Plus, his foreign policy stinks. We should be able to do better than that. I'm not saying I'd use foreign policy as a litmus test and never under any circumstances support someone who doesn't pass that test (for example I'd probably support Jeff Flake for Senate, and would take him over Jim Demint in a heartbeat), but it's a huge issue, and not something that can just be bracketed off as though it's no big deal. In fact, for all the ways that Demint is better than Chuck Hagel, I'd probably take Hagel over Demint just for that reason.