One of the quasi-local homebrew supply stores has a canner they rent out: $20 flat rate plus cost of cans, so right at $40 for 47 cans. I did supply my own beer line and connections because I was canning a sour and they did not want to risk contaminating their own gear. Cans weight about half an ounce, and bottles weigh ~6 ounces, so I save about 1.5lbs. Not quite enough to justify the expense by itself, but cans are a lot more durable.
I dropped the fully-carbonated keg off a couple of days ahead of time. Came by after work, spray-santize the kegs and dunk the lids in a bath of Star-San. Hook up a Blichmann Beer Gun to the keg and gas. Purge each can with CO2, add beer, put the lid on, put it on the seamer, flip the switch, dies seal the lid, and voila, canned beer. Not really any different from bottling from a keg really. One of the guys from the shop did all the filling and I operated the seamer. Really easy process.
Overall, I don't think the seamer makes sense on a single-user situation. Cans only get cheap in bulk and bottles are essentially free, and the price of seamers is still pretty high. The only place it makes sense to me is shipping. If I was worried about "no glass" places, I would package in used soda bottles. My 2¢, anyway.