Are you renting a bass rig or a PA? The question has come up and you haven't answered it definitively either way yet.
If you have decent selection on craigslist, I would try to buy an actual bass rig between now and then if that's what you need. Or find one here/ebay/reverb. If you're in Wisconsin, that makes Chicago area "local pickup" listings more or less feasible (if you have the time and vehicle to go pick them up). There are LOTS of very affordable gig worthy options these as most bassists are technology crazy and balk at any amp that weighs more than a large joint and won't fit in their watch pocket of their jeans. So ALL of this glorious gear from companies like SWR, Trace, Genz Benz (their heavier offerings), GK, and more are available dirt cheap for the level of performance they offer. You can easily put together a smokin bass rig suitable for anything up to medium/large clubs for about $600-700 or less (sample rig, GK 700RB and SWR Goliath 4x10). That's a bigger initial outlay than renting, for sure, but when you weigh that against say, 10-15 gigs (plus numerous rehearsal and playing at home in between and having something whenever you want it and not worrying about GC hours/prices/availability, etc...) unless you play very rarely, it makes more sense to buy.
PA wise might be different. A usable PA costs a lot of money to get going (probably $1000+ even going used), and you're less likely to use that as frequently as a bass rig. So that cost benefit analysis may very well work out quite differently. Then again, rental prices on speakers (GC usually goes with K12s and the like) can add up fast (like $70 a piece). Amps and smaller items are cheaper.
If you need a snake, make ABSOLUTELY sure you know what you need and what you are getting. The number and type of returns is likely to be critical to making everything play nice together.
In my opinion, renting works best to fill in gaps in what you already have or if you really just need something for a 1 time thing and don't expect to need PA gear for a long time, and the cost is worth it one way or another (ie a high paying gig or important show).
