I've had really good luck buying used gear. Your $700 should end up
buying you gear that originally cost $1400-$2000.
(When trying out used mixers, test every channel, and every knob for
malfunctions.- Listen to the speakers loud/closely for any problems)
I'd check here every day:
http://pittsburgh.craigslist.org/msg/
Here's some interesting deals I found in the Pittsburgh area craigslist:
Offer him $700, this should be a great setup.
http://pittsburgh.craigslist.org/msg/341750146.html
(if this does work good, its a steal)
http://pittsburgh.craigslist.org/msg/340004176.html
(nice set for the price)
http://pittsburgh.craigslist.org/msg/336512465.html