If you simply want the colours changed to fit those templates and already have a bridge sorted then it is quite simple (to an extent, there will probably be a lot of css conflicts that need fixing) and would probably take 4-8 hrs. If you need the full visual integration it could take days. Charges per hour vary considerably and can be anything from £20- hundreds or pounds.
You need to state your budget and timescale along with full details of your requirements.
You will almost certainly get a better response over on Joomlancers.
http://www.joomlancers.com/
