I know Monopoly (£5.57) has already been posted by Dean2008 but I thought to increase the list with the following:
In the Night Garden basic plush Igglepiggle and Upsy Daisy dolls as a pack - £7.33 (was £14.99). Cat no: 348/5347
Spears Bingo - £4.37 (was £5.97). Cat no: 390/0619
Spears coin cascade - £3.42 (was £6.99). Cat no: 390/0774
Scrabble Original - £11.99 (was £13.67). Cat no: 390/0516 (already posted elsewhere but worth a mention again!).
Not sure when these prices will change.
I also discovered that the Argos website does not always show the correct in-stock information. Website stated Scrabble was not in stock at my local store but when I visted later in the day, the games were piled high near the counter.