Adam,
Take a look at the EV's Kevin Nichols bought and look at the 18's just as Fred mentioned. You'll need amps, processing, cables and that's it. If those add up to too much money. Look at the Carvin stuff. But the most important thing is you need to sit down and let the "compass" stop spinning.
May I also recommend with said money get rid of iTunes and get some decent software, while iTunes may work you're only making people think anybody can be a successful DJ and as an end result you'll get even less clients because the competition is still going to grow.
For example let's use cars you have $250,000 and you want a Ferrari, you go and buy said Ferrari, but do you have the money for the insurance, maintenance, etc. ????
Thunder and Jon are giving you the truth in a harsh manner without any sugar coating. It's easier to do that as it will wake you up and bring you back to reality. The solutions are there and people are willing to help but people need to know exactly where you're standing and what is within reach you can blow the $6000.00 and never make your money back and the you'll really be up chit creek.