another nw opinion...
I got mines for about 500 with the reverb needing a solder and a bunch non-original, and needing caps... So I've got around 800 in mine (total) and feel like that's fair. Based on what I see on Craigslist, SFDR in decent shape sellers usually ask 800-900 and if it's a collectible, original condition DR people seem to want 1000+. (I figure closed deals probably average 700-800 around here.)
I think you're getting a good deal at $650--I think I might insist on paying uncle 500 and give many thanks... and make him lunch, bring some beers home to share, etc. : )