If you want to go the vintage route, keep an eye open for a tony butler p. it's an awesome bass for the money (299ish new), so a second hand one should fall close to your budget.
There are some wonderful jap basses from the 80's available within your budget that sound gorgeous. Anything from matsumoku is normally worth a punt.
I've had some really great results using Westfield basses and upgrading the pick up. My favourite one cost me a total of less than £100 and gets compliments whenever I use it