Autosynthesis

When I buy a record from HMV, they often come in really heavy dute plastic sleeves with folding tabs to 'close' the sleeve. They are much better than the thin plastic open ended sleeves I've found on Amazon and I want to put all my 'display' records (of which I have 10) in them. Problem is, I can't find a place I can buy them seperately! They are actually very similar to the clear plastic sleeves you find on many picture disks.