I payed just a little north of that for an EBAY 6100lm with a kinda beat up road case this summer. There are some really great features in this amp. Even if you don't use all the channels or features, under $600 is a great deal. Especially when the power reduction gets you to 25 watts.
That's a good price for a very versatile amp. If i had the loose cash i would by that, give it a complete work over and flip it for twice the price. When up to spec these amps are that good.