There's a commercial belt dealership near me that's been able to match up anything I've taken them. From the 120" belt on a Woods mower to the 60 or so for my 1872 mule drive. You need to take the old belt in though because there is no cross reference on the Cub stuff.
The Cub belt was $48 from Cub and $18 from the second source, it's on it's second year.
The Woods belt was close to $80 and $35 from the second source. That one they just referenced the number on the old belt.
Maybe look in the yellow pages for a belt distributor?
Good luck!
Curt