As some have said, watch your local CL. With new higher-end stuff getting so light, a lot of people will sell off their old heavy Peavey gear for cheap. If you don't mind lugging it you can do very well.
Buying new, I'll add my vote for the Soundcraft Ui series mixers. You can do the mixing from your phone. The Ui12 is $339. Of course, you can go cheaper with a small analog mixer, like a Yamaha MG10XU for $199. But I'm a fan of the feedback suppression on the Soundcraft.
Since you're on a tight budget, I would vote to go as cheap as you can on monitors and invest all you can spare for mains. FoH is what the crowd hears, monitors are just for you to hear what you're doing. Kustom is not great stuff, but a powered monitor with a 10" speaker should get the job done, and MF has them for $139 right now. You might want to get three so the drummer can hear what's going on back there.
If you spent $339 on a Soundcraft Ui12 and $417 on three Kustom monitors, and anticipating $100 in speaker tripods and another $100 in XLR cables, you've got about $500 left for mains. Ouch. Well, for just a hair over budget you could get a pair of Mackie Thump 12As, which should do the job nicely at $299 each. Behringer has a 12-inch powered speaker right at $249, which would fit the budget exactly. The direction I had been thinking was the Yamaha DBR10, which runs $399 each. If you went with the analog mixer rather than digital and just got two monitors, that could free up $279 for better FoH, in which case get the DBRs.
Do you have a giggable bass amp? Because if you're running bass through the PA for any purpose beyond monitoring, you should get a sub, and I don't see that happening on this budget.
Oh, and do you already have microphones or does the $1500 budget need to cover them too?