The machine is 8 years old. I think it's *really* hard to get more than half price for a machine that old in a private sale (or on Craigslist), even if it's a Bernina. However, the sellers are probably going by eBay sales. Here is a link to "completed" sales for this model on eBay:
http://www.ebay.com/sch/i.html?_saca...mplete=1&rt=nc
The prices in red indicate the machine did not sell; only the green prices indicate a completed transaction. EBay prices are typically higher than local prices simply because there are so many buyers looking at the machine.
I personally think that $350/400 is a fair price for this machine.