I'll go out on a limb to defend jarland (the admin of mxroute) and say I genuinely don't think it only means 3 - 4 years here. And even if it does, $50 (or even $150) for a 3 - 4 year service is pretty darn awesome.
It's a very tight line to walk, when I intend to offer these lifetime packages and run a company that outlives me. That's why you'll see the price rising on it. I'm trying to find the impulse buy threshold and exceed it to stay on mission. These plans can only fill small unused corners of already profitable servers. Anything more is irresponsible on my part.