Thecus N7700PRO NAS

I have an opportunity to purchase a used NAS Thecus N7700PRO, Probably first introduced in 2009 or early 2010. It has all 7 Bay populated with Hitachi HDS72202 Deskstar Hard Drives 2TB for a total of 14TB.

The Current Model is N7700PRO v2, Brand new price with no hard drives is $800.

What would anyone suggest that I should give for this Used unit?
I am not sure what used equipment such as this goes for, with no warranty. Seller requests cash as is sale.

My concern is that it does not have enterprise drives in it, so that tends to reduce the value. He offered to remove all the drives and sell for $600, but that is only $200 dollars below current price. Which to me should be more like $400 or half the new price.

Anyway looking for some help, opinions on this purchase.

Thanks