Copper tape shielding is not a glamorous job but strangely satisfying and when done right can make your bass almost silent, even in the most death-trappy rehearsal rooms! Outlay - a few quid for the slug tape, perhaps some soldering and some of your precious time.
Oh, and 100% learn to do your own setups. Your basses will end up playing better, the way you know you like them to and for no cost other than your time. If I can learn how to do setups, anyone can.