I'm in exactly the same position, have Fender Jazz and Precision basses and take whichever I fancy when I gig. I also take a Squier Precision as back-up. At ever gig, I tune it and leave it close to me, but it never gets used! I use it at rehearsals sometimes just so it doesn't feel left out. I paid £250 for the Squier, including a decent Fender gig bag, it is one of the vintage modified series.