Beckman,
Welcome. I have seen many grinders of this type for sale in this price range and in many cases below that. You can buy new ones for about 650-700 depending on where you shop. Check Chris Coffee or 1st Line has them, so at that price I personally would not purchase it used unless I could verify the condition. If however, the grinder really is like new and you feel comfortable with that, it really is up to you. It is a great grinder. I too was just in the market for a grinder and got an amazing deal on a brand new Compak K10.
I had been watching ebay, Craigs list etc for months and not really finding any decent deals that I could trust. I personally opted to pay a bit more and get something new. It really depends on the grinder you find, and if you feel it is a version in the condition you want at a fair price. I would ask for a picture of the badge with the serial number on it. That gives you the date of when it was made. I think it is the part of the serial number and on some versions it is the first two digits that reflect the year. If you search these forums you will find a good deal of information on that specifically.
It is worth considering that these grinders are available new and are still being manufactured. I know that on Chris' Coffee website the item is listed here
http://www.chriscoffee.com/products/hom...so_grinder and 1st line has them here
http://www.1st-line.com/machines/home_m...rjolly.htm.
If you have questions on the Compak K10 let me know. I just converted it to doserless and it works perfectly. It is in my opinion, a step up from the Super Jollly as it has 68mm conical burrs vs the 64mm flat. I have used the SJ and several others and now that I have a K10 I would not go back to the SJ.
John