I play in a 5 piece indie/garage/pop band (shameless promotion:
www.myspace.com/capstanshafts). Here's our setup:
Drummer: drums (lol, i don't know drum specs)
Guitar player: Gibson LP -> pedals -> Peavey 100w VTM and Peavey 4x12
Guitar/Synth player: Fender Tele -> so many pedals -> Mesa 2x12 combo, 70's Moog and Korg synth -> a GK 400rb 1x15 combo
Bass (ME!!): Peavey T20 -> some fuzz/od/chorus -> Kustom200 and Ampeg B25b 2x15.
Now, even with all the guitar and synth, my rig is a bit over-kill, so in smaller settings i roll with my 1x15 or 1x18, and it works just as well.
So, really, you have a ton of options.
In my experience, any old busted full of mojo gear is what everyone uses. We've played with a TON of bands and that's the general consensus when it comes to gear. While we're preeeeetty fuzzy-buzzy, a bunch of other REALLY fuzzy-buzzy bands we've played with boarder on the 'wall of amps' motiff. But just start from the ground up. A 4x10 or 1x15 is a great first step... even less if you're a quieter indie-pop band (2x10 combo comes to mind).
Buy used gear.
Your bass is good. A lot of bands play Jazzes... but 'weird' basses are big... haha my T20 fits in that category. I WAS seeing a bunch of Jags... but they break, all.. the... time, so most dudes have gotten rid of theirs or have all the switches filed down or taped into place.