That IS a good deal - certainly better than the "buy it now" Model 1 for $599 that's been up there for weeks waiting for a sucker.
But I guarantee this amp isn't "right" - it will need to be gone through to get it singin' like new. (It has its original power filter caps for one thing.)
I rebuild 'em for $85 - and after that investment then the amp is worth at least the purchase+rebuild price.