I'd add that if you are a newcomer to URB, and looking at acoustic rather than electric it would be a good idea to take along someone who has a little experience to have a look as well. Even with a £500 budget you can look at three basses - one can be a little tired, but absolutely fine, one may be a decent bass that just needs a little TLC (plane FB and a new bridge and setup - that can easily be a couple of hundred though) or a right pile of firewood that will never play right.
I have had friend turn up with a bass and then ask my opinion. I didn't like to give it :-(
I have seen basses repaired by "professionals" that I consider ruined - screwed on fingerboards for example.
Paul