I Love Lucy went for a hell of a lot more than 60 bucks when it was first released.
Season 1 was originally put out in 4 episode, single disc releases, and the huge box set collecting them all was around a hundred bucks.
That put it right in line with the Star Trek releases, which were $119.99.
By the time ILL S2 was finally released, though, I think it was down to 40 bucks for a season in the format we had for the rest of the series.
As for MTM S1's failure, I think Fox overestimated it. I think they expected to do Simpsons or X-Files or Buffy numbers with a show that wasn't in the spotlight like those three. And we've suffered for that miscalculation ever since. They got burned their first time out with classic TV, and they've been wary ever since.