My sister was given (for free) a 1981 GL500 with well over 100K miles on it. The owner said his riding days were over so he'd let it go. He had stored it by draining the carbs and removing the battery, so it only took a new batt. and fresh gas and a little starting fluid and we had her running in about 20 minutes.
She rode it for a couple of years with absolutely NO problems, not even new plugs--NOTHING. Never burned out a lightbulb in two years. She sold it for $1000 and applied that toward the purchase of a creampuff newer CB750 (can't remember the exact model, about a '94)
Anyway I thought that hi-miler Honda was one of the better deals I've seen in quite awhile. It had enough power to run 80mph with no problem, and it got around 50+mpg as well. Not bad.