I have had a problem with my buttercream getting too soft and someonetoldme about this high ratio shortening. Does anyone know where I can buy it?

Global Sugar and CK Kitchens both sell it however you may have a problem getting it shipped in the hot summer months.

http://www.globalsugarart.com/search.php?search=high+ratio+shortening&searchimage.x=24&searchimage.y

https://www.countrykitchensa.com/catalog/searchresults.aspx?Description=hi%20ratio

I would check your local wholesale food store. We have a Kohl's wholesale which is part of DOT foods. I can buy it there at a fraction of the cost of on-line.