£9.85 seems to be the next best offer.
Cheers: The Complete Third Season (4 Disc Set) [go to deal]
Cheers: The Complete Fifth Season (4 Disc Set)http://www.cdwow.com/DVD/cheers-the-complete-fifth-season-4-disc-set/dp/24471/22619091
Edit: See links for 2nd and 4th seasons below. [mr jay t's message]
...and 1st season after that
These are said to be in stock and apparently this is true as I already received a despatch notification. The showed price is £5.99 each. See vouchers for further discounts - at least the 10% off -links are working.
I guess most of you know the series as it's a classic ...or possibly Frasier which is a Cheers spin-off.