If you’ve been looking for an excuse to rewatch all of Supernatural, the complete series Blu-ray is on sale for Prime Day. All 327 episodes of its 15-season run are stuffed into one package, and you can grab it for $101 (down from $120). This collection of Tumblr’s favorite monster-of-the-week show is just one of many Prime Day deals we’re covering, but it’s definitely the one with the most slashfics written about it. See Amazon If you’re unfamiliar, Supernatural was…