Chances are you've already read Digby's post about bloodthirsty right-wing novelty items (e.g., the shirt that says, "Rope. Tree. Journalist. Some Assembly Required"). Outside the Beltway counters with some snarky lefty merchandise (but "Vote Republicans Off the Island" isn't even in the same league). Oh, and all this is discussed at the Mahablog, where Barbara reminds us that hate-as-humor is nothing new in America.
All I have to add is what I said in Digby's comments -- that there's really quite a lot of righty hate for sale. Here are just a few examples I found last year, nearly all still on offer ("Split Liberals, Not Wood," "Save the Rainforest -- Burn a Liberal," etc.). Oh, and check out this item and this one at the Aaron's Case store at Cafe Press. Charming.