Not sure if this is a best buy or a vucher but its the best legal scam I have come accross for yonks:
Morrisons let you spend £100 if you buy £97 of saver stamps which is 30 times the annual return on a First Direct ISA.. As you can buy and spend in November thats a huge APR %.
Now you can use these against a tank of petrol - so thats a £2 quid off a fill up on average for me - so it not just for Turkeys...
Lastly they tear of a page at a time- so in my case the last page cost me £24, if I buy a crunchie bar I get £26 (inc the two free £1 tokens) back in cash, less the price of the crunchie.
Thinking about it, buy 4 crunchies in 4 visits using each tear-off page and you can turn £97 from your credit card into £99 odd in cash in few minutes - and then go buy some more saver stamps!
That's it folks - be gentle
I guess there are other similar Xmas savings schemes to exploit.