Howdy,
While browsing on eBay I ran across item # 110127708717, "190 Pictures by John C. Grabill - Rare Old West Photos." The description state that he arrived in Sturgis SD in 1866 and took pictures of the Wounded Knee massacre site days after it happened. The photos have annotations that were too small for me to read.
The cost is $3.77 plus $4 shipping in the US and Canada. Shipping elsewhere is $6.
One of the several photos shown is of a cowboy on a bucking horse with his "Bonnet String" flying up in the air. Don't know if it is dated or not.