I tend to agree with that sentiment and, in fact, I’m well-known for trying to find quality products and then expecting them to last forever. However, I am not confident that “paying up” for the MX518 will provide you with a mouse that will last for a decade and a half.
I take care of my equipment, but so far I cannot get any Logitech to last for more than 3 years. The longest-lasting mouse I ever owned was an original Microsoft Intellimouse Optical wired mouse (which solved my ball mouse problems so well that I basically had an unfair advantage in pre-millenium games against friends). That mouse still worked last I checked, but the buttons were glitchy; the tracking was still great (for its time). I just don’t like to use wired mice anymore as no longer have a standard PC.
$60 actually isn’t unreasonable for a quality mouse, though. Many people will pay more than $2000 for a nice laptop, so it shouldn’t be unreasonable to pay over $100 for an ergonomic, high-quality mouse and keyboard set.