I do my open mic with 2 1x15w/horn cabs on stands and a Peavey XR600c, a few stands and mics. The mics and PA are for vocals and kick drum only. I like to keep it simple. In fact my gig PA is pretty simple except that I do have 2 SKB cases with amps, compressor, EQ, expander and delay/reverb along with 2 18" subs and a Mackie console. Not too complex.
Lev, don't rush out and buy a lot of stuff. Let the band's progress dictate your spending habit. If you are gigging and getting good money then get some good stuff. You might get by without the wireless and active monitors which are more expensive than passive and an amp.
Some of the best sounding bands I've heard had a small system going for all it was worth. It was good quality stuff but not pricey and the bands sounded awesome.
"No Tele For you." - The Tele Nazi
Ha! Tele-ish now inbound.