Thats the 'how long is a piece of string' question. It all depends on where you are, cost of kit, cost of any remedial work that might be needed on the existing system (earthing etc) and the route the cables will have to take, and how neat you want the finished job. Only the sparky visiting and quoting will be able to give you an answer. However you will be able to ask the right questions based on the info you have in this thread....
Oh and always let your sparky buy the bits. He/she will be happier knowing they bought the kit they like to work with, plus they will know its up to standard and not flea-bay replicas.
Happy tanning..........