Hiya Chelsea,
I think the Wii fit is a great idea to excercise in your home. Not only that the Wii in general is great for a good family and friends night in.
You would need to buy the Wii Console, I got mine from Sainsburys which was £135 with 1 controller and a free game. My Wii fit plus was bought from Game and was about £65 which was for the board and the game iteself. As the console only had 1 controller I bought an additional one which was £25.
If you search on the internet there are some great deals out there.
Hope this has helped xxx