Target has Fallout 3 on sale for $39. Both the PS3 and XB360 versions. The only shitty part is that the offer is only good in stores and not online.
I’m not sure how long the sale is good for. But I would doubt it is much more then a week. You may also want check out other online stores like amazon to see if they will match the price (not the case with amazon yet at time of writing).
So, if you’ve been considering getting this game — do eeettt! — this is a good deal. The sale doesn’t seem to apply to the PC version, which is normally the least expensive version on the three platforms at around $49.