If you are after a retro sound for less than 300 quid, you could go for one of the VM series, either the Jazz or the P with the Jazz and P pickup. The only thing with Squiers is sometimes the quality can be a bit dodgy (I haven`t tried any of the new models though) so mabye it would be better trying them out in the shop.
Or better still, look out for a s/h Yamaha BB414 which has the P/J pickups. The Yamaha basses really are some of the best buys in any price range (as are Ibanez but you are looking for a retro sound) and one of these can be had for less than your budget.