If it's all time best sellers then one reason HOTEOTP sells so well is that it seems to be never out of stock at my local HMV, unlike CH or the elusive FFOGV, as so much of their sales come from High street shops it's the ones that are most available that will be top of the list (still no sign of Formula on the shelves either
)
As for merchandise... surely a cool bright yellow tee/sweatshirt with the Shameless logo is a natural