Wainwright is nice as is Black Sheep. Hobgoblin is gross, far too sweet.
I'm sure the Wainwright was £10 last week / week before?!
I bought the Black Sheep Best Bitter keg in Homebargains a couple of months back for £8. Only one there though. Just got lucky.
Maybe I'm doing it wrong somehow, but every time I try one of these mini kegs, the first pint or two is 95% gassy head, and the last 3 or 4 pints are flat.
Once a keg is opened you usually have to drink it within 24 hours before it's completely flat too