I've been using https://isthereanydeal.com/ for years! I link my Steam profile and it lets me know when my games on my wishlist are on sale on many other platforms that sell steam keys. Hell just tonight I got my normal emails i get and it said that Street Fighter X Tekken is on sale right now on humble for $5.99. https://isthereanydeal.com/game/streetfighterxtekken/info/