A lot of ish breaks on PA's that have been used so I'd be wary of that for $80. Test that beast way out if you get the chance. If you're talking under 50 heads for shows then it sounds like it might be a good deal, otherwise the way they describe it makes me think it'd be inadequate for anything larger.
Let me know how that works out because I'd like to invest in something similar soon but was thinking more on the mobile-dj route. I'm thinking I might resort to the soundsystem technique and just cobble one together from a bunch of old hifi speakers / amps.
Here's a crap picture of one I made a while ago for under $50. Could've used more sub but it was loud enough for 50ish people.
(There's a few more speakers on the side and the ROKITS were used for booth monitoring)
Get handy, go to yard sales / thrift stores and start building some cases, you can have a house-rocking system in no time.