I have never seen anything on sale. Pizza is the premium currency in Card Hunter, and is purchased. It can be used to purchase more adventures (with guarantied rewards), a special account boost that gives an extra item whenever you earn items, and character skins. It is not required to enjoy the game, but it does have uses. If I missed anything, someone else can add it. Hope this helps!
BM had a pizza sale early on, but it hasn't been repeated. Pizza may be purchased by clicking the red + next to the pizza slice, but as fatcat says it isn't necessary to progress in the game. However, if you want to buy pizza to support the game, I'm sure Jon would appreciate it. Welcome, and Good Hunting!
Welcome to Cardhunter! I recommend buying the bundles, those are the ongoing sales. Otherwise, I recommend investing in some pizza to buy the treasure hunts. Also Mauve Manticores have some great guaranteed loot drops.
