Alot of people have reported Sam's Club has the PS3 version for least than $26. But YMMV unless you unfortunate to live in a place like mine where all the stores seem to want to keep it at $53.77.
Just noticed where I posted this. I heard they might have already closed the Sam's in Canada so if they are already closed sorry.
There is no time limit on it. A Sam's can just decide if a game is taking up space for to long to lower it price. So if a Sam's close to you has lower it it will stay at that lower price. The problem with that is there is no guarantee which Sam's what low prices on Fallout 3 even though it seems like the majority do.
It has been reported on RFD that Fallout 3 CE for PS3 will be the doorcrasher at EB Games on Monday. People are saying the price will be $39.89 but it has not been confirmed.