This seems like a decent deal; both Marvel's Guardians of The Galaxy and Marvel's Avengers for $50.94.
According to SteamDB, Marvel's Guardians of The Galaxy's all time low on Steam was $44.97, and Marvel's Avengers all time low was $21.18. This seems like a pretty good price for a bundle that includes both games. Neither game is currently on sale; it is only this bundle which provides the discounts to both games.
If you want the Deluxe/Endgame Edition of both games (includes M.A Endgame Edition DLC Pack
and M.G.o.t.G: Digital Deluxe Upgrade), this bundle is also on sale:
Marvel's Guardians of the Galaxy + Marvel's Avengers Deluxe Edition - 57% off, $79.99 (Was $187.85)
Marvel's Guardians of The Galaxy
Fire up a wild ride across the cosmos with a fresh take on Marvel’s Guardians of the Galaxy. In this action-adventure game, you are Star-Lord leading the unpredictable Guardians from one explosion of chaos to the next. You got this. Probably.You play as Star-Lord, so nothing’s off-limits with your bold combat style, from Element Blasters and jet boot-powered dropkicks to tag-team beat-downs. With the Guardians fighting at your side, call the shots and overwhelm your opponents with signature attacks. Meanwhile, the consequences of your decisions will range from light-hearted to downright unexpected as your journey unfolds.
Marvel's Avengers
Assemble your team of Earth’s Mightiest Heroes, embrace your powers, and live your Super Hero dreams.Marvel’s Avengers is an epic, third-person, action-adventure game that combines an original, cinematic story with single-player and co-operative gameplay*. Assemble into a team of up to four players online, master extraordinary abilities, customize a growing roster of Heroes, and defend the Earth from escalating threats.
I thoroughly enjoyed GOTG game! Avengers not so much.