Cats will sleep where they want, when they want.
There's no need to buy her a bed, as she will sleep on the couch, floor, laundry basket, on your bed, on the window, etc. ^^ What you should buy your kitty, (and they only cost about $5), is a cardboard scratcher. Mine love them. A couple of toys (mine like the balls with bells in them and the "fishing pole") to help keep her active is a good choice too. ^^
I've had cats all my life, and got my first two (on my own) about two years ago. They don't scratch anything they aren't supposed to and are quite well trained. xD If there's anything you wanna know, feel free to PM me. ^^