I found this thread:
http://sewing.patternreview.com/cgi-...ard.pl?t=27174
which indicates that this model is commonly called the Viking #1 (as opposed to the #1+). I did a search of completed listings on eBay. This is a tough call, but just from my cursory survey it looks as if this was a top-of-the-line machine 18 or so years ago and might be worth somewhere around $300 (the $700+- $100 in the thread was posted in 2007 when the machine woudl have been more valuable).
You could probably get much better info by joining the vintage Viking group at groups.yahoo.com; however, it might take awhile to get accepted into the group.
Edit: Actually, I read that thread a little more closely and someone purchased the model 1200 for $300 in 2008. This would lead me to a currently valuation of maybe $150 or so (because electronic boards, when they go out on a machine like this, tend not to be replaceable).