Hi
I wouldn't suggest buying one unless you are prepared to splash out a lot of money on a high quality one. They have them for a couple hundred pounds but they are nowhere near what you get in the gym and dont get the same results.
You can hire one for home at a place like hirefitness dot co dot uk (not sure if we are allowed to list sites!) to see if you like it, or most gyms have them now so you can get a free day pass and try it out. They do definitley work! Make sure you warm up for a while first, I didnt the first time and I was so sore afterwards.