There are a ton of dealers claiming to sell refurbs.
It all depends on the definition of refurbished used by the seller. A dealer who takes a used one in on trade might test it, repack it, and call it refurbished.
Canon takes returned cameras from dealers, gives them a thorough check and repair, and packages them with all the manuals and accessories that they had when new, and gives a 1 year warranty. They do not reveal the number in stock. There are some dealers who purchase refurbished cameras from Canon for resale, these are Factory Refurbished.
With some products, there are huge refurbishing centers in Mexico that refurbish used or broken products and resell them to dealers. They process everything from cell phones to electric mixers. These often find their way to ebay. As far as I'm aware, Canon does not do this with DSLR's, but may with P&S cameras.
I once considered buying a certain product for resale this way, and discussed it with the refurbishing company. In the end, I decided that markups were too low and it was a dog eat dog business.