I looked into doing this sort of thing. I got quotes from all over the place in Greece. At the end of the day it would have been cheaper to buy a boat and resell.
Having said that.... in todays market, when reselling might be problematic, ......

All in all there's maybe not a lot in it whichever way you go. But I know it'll be expensive.
For a 10mt charter I imagine you'll be looking at around Ł16k plus insurance etc etc