I'm seeing A770s for about $500 - $550. Where did you find a refurb one for $350 (or less since you're also including other parts of the system)
It's out of stock now unfortunately, but it does seem to pop up again from time to time according to Slickdeals: https://slickdeals.net/newsearch.php?q=a770&pp=20&sort=newes...
I would probably just watch the listing and/or set up a deal alert on Slickdeals and wait. If you're in a hurry though, you can probably find a used one on Ebay for not too much more.
I'm seeing A770s for about $500 - $550. Where did you find a refurb one for $350 (or less since you're also including other parts of the system)