Hi Corn,
Yes the 65's are definitely cheaper and that's for a good reason, they're not that popular due to their sizing and weight. As you said the 45 is the preferred weapon of choice and the preferred unit for the Flippers out there that are running rampant.
There are two variants of the Model 65, the one pictured which is the earlier variant and an absolute PITA to work on with the twin coned clutches and then the preferred second variant without those two massive clutch bodies.
The Supercuts and 65's are great for straight running while the 45 is far better for traveling around curves at clutch slipping slow speeds. The 65 can't have it's clutch slipped as does the 45 and this is what it's all about in today's landscaping designs.
Cheers,
BB.