Value would depend on many things as you know (title? engine/frame/trans#'s match?) but these bikes in general have a strong market. I'm not good enough to identify the exact model based on that picture (R50/R60/R69, with the latter being most valuable) but I seem to remember that the number of fins on the valve covers was an indicator as to weather it was a high performance model or not.
For reference, the 1964 R50 in our mutual friend's garage brought in offers from $3500 to $5000 (though it was in better condition).