I don't know where you're getting $600 - most Glock 30s can be found new in stores for between $400-$500.
If that's out of the budget, Kahr makes some excellent inexpensive small polymer-framed automatics in .45 as well.
Even Ruger has a somewhat compact .45 that is easy on the budget. Though Rugers tend to be a bit heavy, they're some of the most reliable arms out there. And you can use one as a hammer and it won't care.
Automatics really aren't all that expensive any more. A Ruger will cost about the same as a good derringer in a real caliber.
Seems pretty reasonable. I haven't even been to a shop or looking for well over a year, maybe two now.