That's a 1980 serial aright, although, as far as my research has shown me, the '80' is not the year, by the late 70's they had dropped to a single digit for the year, the year is just the '0'
$110 sounds a little more than I would pay for a mustang, but if it's working, that's a bonus.
I generally don't pay more than $20 for a mower, and I tend to be able to find what I need for that.