Update: Tesco has returned the PS3 version of Saints Row 2 to GBP 39.97.
Earlier, the online retailer had offered the game for the minuscule amount of GBP 15.97, which caused rather a lot of excitement.
Now, however, the Xbox 360 version is the cheaper of the two at GBP 34.97. Or, alternatively, there's the PC offering for GBP 24.97.
Saints Row 2 is due for release this Friday and is really very good. You might have even noticed our Saints Row 2 review this morning, in which the game was awarded 9/10.