Do you ever get work through recruiters? Do you find their rates to be less? Whenever I get contacted by a recruiter and I tell them my rate they freak out. They say "The customer has a stretch budget of $40/hour for this contract" like that's some huge amount.
Let's say they get a budget of $80/hour for the project. Their goal is to sell it to you for as little as possible so they can take the difference. So they're always lying to you about the customer's budget, because in truth it's about them maximizing their profit.
I once had a recruiter offer me $25/hour. I laughed at them and told them to not call me back unless they could do $60, which at the time was my rate. They called back about 15 minutes later and said the client had increased the budget and they could do $60.
I've landed two gigs with recruiters at about $75 / hr, and I've made it clear that I'll be raising my rates after several months, assuming things are working out. I think it just depends on the type of work you're doing. I would imagine iOS, Rails, Django, and anything other than PHP would probably be more.