God damn! My company in Odessa, Ukraine is going to pay me ~$1500 for full hours, but they actually count time, so potentially even less. And they are trying to sell me as a team lead for US/Canada based company to clean up the code from 15+ years of Indian dev (which is a bad situation to say the least)!
So I don't know how much the management costs, but an estimation of $4000 per head/month is pretty realistic if not cautious. If you are eager to work with freelancers, you can get your work done even cheaper. Same qualification, less staff. But it depends on the amount of work: see, if you can search oDesk for talents vs hiring a company. Starting from 5 developers it could be easier to get by with a company, that will manage the whole thing. If less, just contact them individually and make one of them responsible.
If you want to evaluate from current salaries, please take a look at this page (it has data for most of IT in Ukraine - shows lower, median and high-level expectations, if you can't figure out what's written in Ukrainian):