I purchased the Booking Calendar script which takes online payment via paypal and credit cards etc - which on its own, is already a great script that works extremely well and represents good value for money (compared to some of the estimates I received from odesk). But the service was also 2nd to none.
Installation was just a couple of clicks which required no knowledge and out-of-the-box it has many tweaks that you can implement to suit your purpose.
I contacted them for a couple of additional modifications to the script and daily I had replies from a knowledgeable guy called Kosta.
For anyone thinking about purchasing - do it - if you find a script cheaper elsewhere it is probably stolen!