I suspect that the reason the 10" blades cost so much more is economy of scale, they sell lots more 7 1/4" blades than 10" blades. I've used the same table saw 10" blade for several years, been sharpened once. For the cost I'd just buy another 7 1/4" blade, not pay to have it sharpened.

Bill H.

Those of us who are old enough can remember the days (and burning smell!) of cutting wood with steel-tooth blades on the tablesaw. In Canada, a good carbide-tip blade cost near $100 (in 1970s dollars) and was far from narrow kerf, so a powerful tablesaw was needed. I think my Grandad never had more than a 3/4 HP motor on his tablesaw.
We are lucky to have all these relatively cheap excellent blades nowadays.