Melanie, how long is a piece of string? prices depend on where you live, who you get to do it and what guarantes they will give you on the work. If you are a novice plumber, how willing are you to grovel, get wet and dirty, skin your knuckles and maybe flood your house?. if you do want to try it yourself, lots of places run plumbing evening classes and there is a website whose name escapes me (but mikewith knows it) where you can find out how to do it.....honestly, the best of luck. last comment, are you in a flat and how would your neighbours react if you leaked water into them or affected their water supply?