It's been like $20 all over the place at different times over the past few weeks. Keep your eyes peeled for deep discounted digital sales. Borderlands 2 is a Steamworks game which means every PC copy needs Steam.
Speaking of which, MacRumors really dropped the ball on this news article. The fact that Borderlands 2 is Steamworks-enabled less than two months after release is HUGE. Screw Asper and their BS online store. If you're not playing this game on Steam, you are doing it wrong.
Oh TO HELL with Aspyr and their racket. They've ported so many games to Mac that aren't Steamworks-enabled. Maybe that's not a big deal to you, but I already own those games on PC and should be able to play them on my Mac as well. Thank god Gearbox must have some sort of deal to force them to release on Steam.
Every time I see that port of Batman: Arkham Asylum for $50 or whatever I rage.