If you're in the need (like me right now) to print +300 photos in several formats, even shopping at best prices around me, that's something like 150€ for them. For that kind of price I could get a nice home printer, supplies, and afterwards just keep the printer for the future.
And they'll need to "realign the heads" and "clean the nozzles" at least 17 times, which will consume hours of your time, paper, and probably another whole set of cartridges too.
I battled with Epson and HP inkjets for years - I haven't looked back since I bought a small black and white Brother laser a couple of years back. No more wasting time, no more new cartridges every 5 pages - you just hit print and it prints.
If i recall right, i even read somewhere here on HN that someone basically printed full page color prints all day long and HP happily keeps sending him fresh cartridges, which is, at the rate he is paying monthly, a steal...
I guess nothing stops you from ending your membership after you're done with your printouts :)