Yeah, you may need to know what you are going to have before you set up gigs, but I set up my first gig without having any equipment, so it is possible. I offered my "services" to a bar that was losing their KJ, even though I didn't actually have any services to offer. I basically BSed them, but it all worked out!!
Here's what I would do with your budget. Note that American Musical Supply will ship all of this to you free with no tax AND they will break up the price into 5 monthly installments for free, so you can pay it even easier, especially if you have a gig going and have some income. So, here's what I would do, with links:
MAINS:
I love my Yamaha S115Vs. 500 watts program per channel and the best bass in a 15" cab out there in my opinion. $326 each ($652)
http://www.americanmusical.com/item--i- ... 6_386.html
MIXER/AMP:
Yamaha EMX512SC Powered Mixer with Effects (500 watts/channel, onboard vocal effects) $569
http://www.americanmusical.com/item--i- ... 9_398.html
SONIC MAXIMIZER:
(This will boost the highs and lows of your overall mix and is a quick and easy way to immediately upgrade your sound:
BBE 362 ($99)
http://www.americanmusical.com/item--i- ... nd-27.html
So that's your main system for $1320 flat.
You'll then need all of the cables, mics, speaker stands, and a CDG player (you may already have some of this).
You can find all of these things on the same American Musical site EXCEPT the CDG player. To start off, you should be able to use any decent one-tray CDG player. You'll save alot of $$$ on the player by buying it off Ebay. I wouldn't trust anything under $80, but as long as you buy from a reputable seller with good feedback, you should be fine on the player. Remember that the mixing amp above will take the mic input and has built-in vocal effects, so you won't need these bells and whistles on your CDG player.
Here is a good deal on some good sounding inexpensive mics:
Samson R21 3-pack ($49)
http://www.americanmusical.com/item--i- ... nd-27.html
I started out with these mics and 2 of the three of them are still going strong after 2 years. Once you have some cash flow, I'd look into upgrading to a Shure S58 as your main mic for the singers, but for now these are very reliable and sound good for the $$$.
CABLES: You'll need the following cables:
(2) 25 foot speaker cables (1/4" cables) for the main speakers
(2) 25 foot XLR microphone cables for the two mics
(2) 3 foot 1/4" cables to hook up the sonic maximizer
If you buy these cables at your local guitar center/sam ash, etc., there are usually brands they carry that are only about $5 more than the standard cables, but they have a warranty where if they go bad you just take them back where you bought them and they hand you a new set. That extra investment will save you a ton of $$$ in the long run.
Spend the rest of your budget on CDGs. If you need some suggestions on some good core sets to buy, let me know!! Also, spend $50 on a book program like kjpro (kjpro.com) and making books will be simple for you.
So, that is a good start. You should let some other peeps make suggestions and go with whatever you think is best, but this is what I would do on your budget.