Here is a 5x7 b/w Richard Burton SP on eBay from VINTASIGS1 for $145 (OBO) with JSA, followed by 3 authentic exemplars (click to enlarge). I would not go anywhere near this. There are some rather odd JSA items up for sale...
I realize that this thread is several months old, but I wanted to piggyback on Eric's good exemplars included above to contrast this image of a lot coming up this week at IAA's March auction. This IAA one needs a pass from my perspective. Maybe others would disagree.
It's not explicitly stated in the IAA lot description, but I'm wondering if the blue ink is a tip off that it's part of their French collector's output....