Flew from East Midlands a few week back and they have stopped giving them away. They now have vending machines where you can buy them cost was 50p but dont know how many for, could be each.
I would expect other airports to have gone the same way by now, or very soon.
Found this site on t'internet:
http://www.captainbags.com/q-20-x-20-air-travel/cat_10.html
10 bags for 0.73p
25 bags for £1.74