Calling Dr. SupplyandDemand!

I'm looking at the cover of a catalog from the teaching company--you know, those guys who have more sales than a furniture showroom.  It says:

Save 70%

on courses by some of our

Most Popular Professors!

But isn't that backwards?  Didn't I learn in Econ 1A that if demand increases, the price will rise?  Shouldn't it say:

Save 70%

on courses by some of our

Least Popular Professors!

[And actually, they do have a kind of "remainder shelf," where they shovel out some courses at $10 each--not, I suspect, their "most popular professors.]  Or, failing that

Most Popular Professors

70 Percent Surcharge!