Well steep at £7k bet he wont shift it at that price. 2nd gear can be solved by Molyslip and oil change.
As said above you will get a very nice 350Z GT for that money,
there are a few nice ones on here for sale at the moment.
I would always try and buy one from a forum member as there is a very good chance its been well looked after.
Good luck with your search, have a read through the guides on here about buying a Zed.