Three years ago I paid $19.95 for the upgrade from v.2 to v.3, and I got v.2 as part of a MacHeist.com bundle in 2013, when it effectively cost me nothing.
After 5 years of quality service for $20 I figured it was worth upgrading for the $49.98 charge (after $45 upgrade discount). So I did.
So far so good. Seems a bit speedier. Still trying to get used to the new look of the menubar drop-down though…