The cusp of the matter is that your gear doesn't matter price or quality wise too much.
It's all about finding "the one" really, or as close as possible to the one, for some that'll be a £2500 Celinder, for others, a sub £200 SX.
Once you find the one, that's where it matters as you can then focus on bassplaying and not the instrument itself.
I'm a terrible bassist, but currently I'm not really enjoying my jazz basses, which means I'm not improving as I'm not playing them as much as I should be. Once I find the one or ones that I get along with perfectly, then I'll end up playing more and improving. You can only do so much on an instrument that you're not enjoying.
Same goes for amps and cabs, although it's less of an issue as it's not the instrument.