If you are doing apples to apples and actually know junior or senior developers with a $50 hourly in the Bay Area, tell them to double their rates today. That still doesn't get them to market but hey baby steps like doubling their rates are a good way to get started.
But it's mostly the travel time that kills them, I think.
"What we should expect"? What does this even mean? What do you expect someone who provides a service that is in demand charge or make? Why should they make any less than what the market is willing to pay?
The same goes for competency in many other jobs, like plumbing and yard work, that may be considered "unskilled" or not. The difference between some of these is that you often hire cleaning or yardwork services on a regular or scheduled basis, so you have a nice feedback loop on determining their value (both monetarily and for keeping them around/finding a new one). Versus services like plumbers, who most people only call when there is a problem (that is, no one keeps a plumber on retainer).
So, if you knock a third of the price in OP off - and say that's what the company keeps - you'd be looking at more like $20-23 an hour in Bay Area.
Then you've got travel time to count in - say it takes them a half hour to get to your house and a half hour back to base. If they work your house for two hours at a stretch that's another third. So, 40 over 3. That'd get you down to $13 an hour.
And then you've got to ask how many hours they can really fit into the day.
EDIT: Just think on how may real billable hours any of those contractors have in the year