GAS = Gear Aquistion Syndrome
And for £500, just get out and about and try them in shops.
Jazzes and P basses are the standard basses that everyone tries but there are lots of others on the market (Warwick, G&L, Musicman, Rickenbacker, Cort, Ibanez etc.)
Also don't be afraid to look further afield like on here and ebay, can get some 2nd hand bargins.