This seems to be a great deal, which i ordered from pcworld last week and it seems to be the cheapest dvd-rws i've found that is available for delivery.
They actually cost £2.97 per set of 10 but you require to pay £3.99 for shipping but you can have upto 3 sets of a single item with no additional delivery cost, so you can either have:
10 dvd-rws for £6.96 delivered (approx £0.70p per disc)
20 dvd-rws for £9.93 delivered (approx £0.50p per disc)
30 dvd-rws for £12.90 delivered (approx £0.43p per disc)
Don't forget to use quidco for a 6% cashback :)
It seems this deal is also available instore without the need to obviously pay for shipping, so log on to the website and type in your postcode to see if they have any available in your local store and look out for other dvd-rws that may seem better value but are only available for instore collection but i've listed this deal for delivery purposes.
Hope people find this deal helpful and please remember to vote the deal hot and give me rep if you like my findings.
Thank you and have a nice day