A 400 can provide cheaper and quick thrills if you are just looking for a bit of fun, Granted it starts to get more expensive when if you were looking to start racing on one. My first zxr (The one i crashed at mallory recently) cost me £800 last winter and it didnt need anything doing to it, You should be able to pick up one for around that money or less now. Failing that I would look around for a cheaper 600, maybe something pre-injection or steel framed, again a cheap and cheerful way to get involved and at the end of the day, something you aren't really going to fret about
when you throw it at the scenery
.