Wait for 75%. They've already been 75% off. I forget where I got mine from but I believe Newegg and GMG have both had them 75% off before, minus the recently released one of course.
For the uninitiated PC gamer newbs who are recent console refugees, newer EA games are not on Steam because Steam changed their terms of service some time ago to require that if you sell the base game then you must sell the DLC as well or else you can't sell the game on Steam. EA refused to comply and some games like Dragon Age 2 got yanked while others after that point just didn't get added at all, like ME3. Certain games already on Steam before the change in terms, like Sims 3 and older Bioware stuff, are grandfathered in and can still sell the base without selling the DLC on Steam but going forward it's not going to happen. So far EA and Valve have been playing chicken for almost 3 years now and neither is willing to blink.
Edited to add: The sucky thing about EA monopolizing the DLC is that there's no competition and it almost never goes on sale. Seems to be part of their strategy to get you in the door with a cheap base game and then once you're hooked you're paying full price for DLC. For Bioware stuff there really hasn't been a complete re-release with all DLC since Dragon Age Origins: Ultimate Edition AFAIK. That ME triology is not complete with all DLC, though which DLC you get varies from platform to platform.
FWIW, the way the Bioware DLC works is if you own it on one platform you own it on all of them, so if you buy DLC on PS3 you also own it for 360 and PC and vice versa. It all connects through your Bioware account in the game itself, even for the games on Steam.