This deal is hard to obtain, might even be impossible. Right now SCA are running a 40% of socket sets and some stores still have some old stock of Sidchrome. Also a search on the website doesn't show them (although a google search "supercheap auto sidchrome" give some valid results) and are not showing any discount but it can be discounted by staff - from 3 only one was discounted.
Some ends up with a very good price, but I don't know if are still available somewhere.
On SCA site is 40% off socket sets excluding Kincrome, but as far as I can see they don't have Kincrome socket sets (just a 10mm emergency one). It's just a guess that it should have been excluded Sidchrome since it's weird to exclude something that you don't stock (although there is not much stock of Sidchrome either, and I don't think that will be anymore since it's out from brand list).