Thanks to puffopuffo for this one.
CdWow have most of the newly released 4 disc complete season sets for £7.99 each. Seasons 4, 5 & 8 are priced a little higher at £8.99.
Use the link to bring the prices down by £1 per season making the entire series a respectable £76 delivered. Quidco @ 6% if you can work out how to get there!!