If it has Harley Benton written on it buy it, was my motto. Not any more obvs.
The Sandberg Electra bass I bought here is alleged to be from their budget range but it's as good as anything I've played.
As to must avoid that tends to be any bass over £500 second hand.
I say tends to be because I just broke that rule... twice.
I don't avoid any brand, they're all quite capable of producing a gem. Having said that, I have yet to find an MXR pedal I like, and I know they're highly and widely respected.
Oh and Ashdown is a great company and a fine builder of amps and cabs but can't seem to make an envelope filter I like.
In the end, buy second hand, do your research to ensure you're not paying over the odds, sell it if it's not to taste. Use reviews to discover products you might not otherwise hear about but don't trust other people's opinion.