Bose? Really?
For $1,300 I would look at Mackie, Yamaha, or SoundCraft mixers, and Yamaha, QSC, or select Behringer amps. There are many different speakers available.
What type of music does your band play? You can get a pair of
Yamaha S112v 12" speakers for a pretty good price but they aren't going to rock a room with bass. You need a sub for that. The
S115V's will fill a larger space but cost a bit more.
A pair of
Yamaha A12M's would make decent monitors. There are others I would choose, but they are not in the budget.
A
Behringer EP4000 is probably one of the more powerful amps in it's price range. You could use it to power both the mains and the monitors.
A 12 channel mixer like the
Yamaha MG166CX would allow for expansion in the future.
The S1112v's, A15M's, mixer, and amp come in at around $1,799. You can get cheaper gear but I see no point in investing in crap speakers and a lot of cheap PA speakers are pure crap. I have little experience with Behringer PA speakers. They may have some good ones but I wouldn't know. I do have experience with Behringer mixers and I avoid them. The ones I have used were not well built.
You also have to consider the cost of cables. Mic cables add up fast. Even if you buy them from
Monoprice.com, the cheapest very good quality cables I have found, it can still add another few hundred dollars. That's not to mention a snake. If you aren't placing the board on the stage you will need a snake. A decent one is $200 or more.
Microphones? You didn't mention them so I assume you have them already.
You might check locally for used equipment. Besides the microphones and cables, much of my PA system was put together with used equipment.