I went into Argos today and bought £100 x 3 in vouchers. Each time I got a £10 voucher free (the deal that's on at the moment, previously mentioned on this site - thanks to the poster). So I ended up with £330 in vouchers for £300 cost to me. I then spent that on the Playstation 3 with two games and got ANOTHER £10 voucher. So you end up with a PS3 for £320 + you get a £10 Argos gift voucher.
Please note that when I first tried to buy the gift vouchers, the lady behind the till did not think that buying gift vouchers was included in the 'get £10 gift voucher for every £100 spent offer', but when I showed her a print out of the terms and conditions from the Argos Web site (http://www.argos.co.uk/static/StaticDisplay/tag/HP1_main1a/includeName/freegiftvouchers.htm) and pointed out that only buying gift vouchers with gift vouchers is excluded, she let me go ahead. You could also use this offer with the 40GB version, or indeed any product over £150.
If you are reserving the PS3 online, make sure you include two games (as one game - Heavenly Sword - is only shown on the 60GB PS3 special offer page). I got Heavenly Sword and Motor Storm (I know Resistance: Fall of Man is also an option).
Once again, thanks to the original poster who pointed out that Argos had a £10 gift voucher offer on.