Opinions will be just that; an opinion. Why? Without seeing the bass, playing it in my hands, ensuring the bass functions, as delivered from Ken, is a difficult opinion to give at this point.
On the other hand, if this bass is in excellent shape without any mods and/or damage, and set-up well FOR YOU, then the price sounds good to me. As far as current production Smith basses; that model would be in the lowest dollar range (price-wise).
Another option would be to locate a Smith Burner Model. This is a discontinued model, however, they pop up on eBay and other sites occasionally: A 4-String Burner in the $800. (excellent/original condition) is a possibility.
Also, the KSD 4's can be found on eBay from time to time in the $400. - $600. range. NOTE: KSD's (Ken Smith Design) are not made by Ken, but designed by him. I believe they can also be purchased new via Brooklyn Gear. See additional info here from Ken.
http://www.kensmithbasses.com/KSD/KSDdefault.htm
Good luck!