I got my 580 for $529 last year and I think they were $559 at that point. But I got mine from my rental yard that I do a fair amount of business with. They're also a Husqvarna dealer.
The problem with online sales from some manufacturers is that the warranty is automatically voided if the unit wasn't sold by an authorized dealer, assembled and fired up by them prior to delivery to the customer. Not sure if that's the case with Husky.
The 570 (and 580) are big heavy units but should last you a lifetime of residential use if treated well and stored properly when not in use. I don't think you'd be disappointed with the 350 and you'll be blown away by the bigger units, no pun intended, lol.
On a side note: The hip belt on my 580 is showing wear where the flexible portion of the blower tube rubs against it. I'm worn through the fabric to the stiffener in a spot about 1/2 inch long. I'll see if I have any more sail repair tape around...love that stuff for fabric repairs!