I do some android development in my spare time, both for fun and for money. I am a full-time java developer, too, if that matters.
I would like to try make some BTC from Android development. Anything goes basically, but I will be less likely to take on big projects since I would like to be able to finish them properly.
I would personally prefer hour-based billing, but that is a mess for the buyer, so I can do an estimate for your ideas and give a price in BTC. This is also why I don't like "too large chunks", its a risk for me if I underestimate the time to completion.