I agree with alex

Investing in a 2.4 ghz set will save money in the long run.

However if you want to start of cheaply. I think you can get by with a 40mhz system.
If no one replies I do have a Sky sports 4 lying around. I dont use it any more and it only has three channels working. Also dont remember where the charger is and did I mention its about 6-7 years old?
I would suggest picking up one of some one else.