Okay, so you want to buy the stuff anyway. If you answer a few questions, you will get better suggestions from the board:
* how many times a month will you be using the stuff for DJing, how much karaoke?
* how portable, will you be using a trailer, van, car? 1 or 2+ person load in/out?
* do you expect all the gear to last years, or are you okay with less expensive stuff even if you know you may have to replace some components within the first few years?
* do you need effect/stage lights or dance floor lights?
* if you know your budget, post that too
* are any of your venues really small, e.g. no stage for karaoke, or not enough floor space for a table, a couple racks of gear, speakers, and whatever lights you want, for DJing? if so, keep footprint in mind too
Without knowing any of that stuff, here is what I would suggest to keep your expense down, because so far it sounds like you only have one job that is too big for the stuff you already own, so let's not talk you into buying a lot of stuff you might only use a few times a year. Here is the stuff I suggest, and links to musician's friend for each thing. That is my favorite online vendor.
* 1 Behringer MDX4600 compressor, see my previous post
* 1 Behringer DEQ1024 graphic EQ, ~$200
link
* 1 Behringer DCX2496 digital cross-over, ~$300 [URL=http://www.musiciansfriend.com/srs7/search/detail/base_id/104116[/URL]
* 2 or 3 Crown XLS 402D amps, ~$400 each
link
* 1 or 2 Behringer B1800X Pro 18" subwoofer, ~$350 each
link
* 2 Kustom KSC 215H 2-1/2-way cabinets, ~$200 each
link
* 1 Behringer FBQ2496 digital parametric EQ / feedback suppressor, ~$150
link
* 2 Kustom 15" stage wedges, see my previous post
* one mixer top rack case for signal processing
* one amp rack, or put amps in the first one if floor space is at a premium
* cables, mics, etc. etc.
Now all that adds up to a bunch of money, so hopefully you will decide to wait a bit or even hire a band PA guy to do the sound and just give you an input for your music and mic; that is a lot to invest in gear if you are not sure how often you'll use it!
And the stuff I suggested above is pretty similar to the simplified system I have put together for lending out and using where there is not a lot of floor space to work with. I would not ordinarily use something like an automatic feedback destroyer, but if the user might be inexperienced, it can save the show.
Also, if you buy all that gear, eventually you will end up replacing some of that Behringer stuff. I think that's fine because (I assume) you are trying to grow your business and probably don't want to break the bank doing it. If any of those pieces of equipment break in the middle of a show, you can unhook that piece and deal with it later, no show-stopper.
Now, that is what I personally would use for that size crowd, with some simplifications for ease-of-use. I am not saying it's the best setup for you. I think you are pretty ambitious to buy a ton of gear for just one gig, but then, I have upgraded a lot of my stuff for one band too
Oh yeah, and if you buy all that you better have a cargo van or a trailer to transport it in. I use a trailer with a ramp door, cost about $3000 at Home Depot. So now you are into real money! ;P