http://www.pilotjobsnetwork.com/jobs/Mesa - First Officer (copilot) in their first year at the company makes $19/hour, and is guaranteed 76 hours/month. Equates to $17,328 pre-tax. It's why so many regional pilots commute, because they can't afford to live near the major airport which they're based at. The result is fatigued or sick (no pay if you call in sick) pilots operating these flights.
But hey, supply and demand. They wouldn't be able to pay so little if pilots weren't applying, and that won't change anytime soon because flying at a regional for a few years is a way to build hours and move on up to the mainline airline.
I'm pretty sure that "per hour" is "block hours", such that they are paid only when the door shuts.
So there's a fair amount of waiting around that's uncompensated. There is a per-diem, but I don't think it goes beyond average cost for meals, lodging, etc.