Usually have a look around when I get edgy from not having purchased TFs for a while to round out my collection, but most of the things I need are from sellers in the US, and they have a way of charging outrageous amounts to ship to Canada, hence why I don't use it much anymore.
Although I do find those rare instances where the shipping charges are more than fair (recently payed 8$ to get a G1 Gnaw in from Texas), hence why I go back from time to time.
And yeah, free shipping is great but not necessarily a deal breaker as such. Especially if the total, including shipping, is still under the price of a "free shipping" auction.
And the only time I've ever sold an item there was during the time of car Robots/RiD. eBay is all about purchasing for me, not selling (although I would need to get rid of a couple pieces at some point.)