Ask HN: What's a fair/common hourly rate for Android Development?

I've been developing and designing Software, Web-Apps and Add-Ons for customers for 5 years now. I usually charged 50EUR/h for non time-critical stuff and raised that to 70EUR/h for critical requests and Sysadmin work.

a) What should I charge for developing and designing native Android Apps?

b) Do you charge differently for Cross-Mobile Development using Frameworks like Qt/PhoneGap/Sencha/Titanium and similar?

PS: Do you know some free/opensource software for running your business?

I currently use Dolibarr [1] and it's awesome, but it's code is unmaintainable and it's not customer friendly. Contract/customer/invoice management is all I need.

--

[1] http://www.dolibarr.org/