"...Simply amazing stuff. Then, for a while, nothing at all."
I don't think it's just the shops either. It will be like that on Ebay, Craigslist, and the like as well.
One weekend I found 5 things on Craigslist that needed to be purchased and juggled to make it happen. Other times, it's like like a funeral parlor.
Same thing with Ebay. Back in November, I couldn't buy enough stuff, then in February, it's like Ebay put a moratorium on listing canister vacuums.