I think you hit it with "enough corporate business" and "supply & demand". Keep an eye open, but they could drop prices. However, that's one of the busiest travel times so they must feel they can charge that.

Why can't you just rent with Hertz or National?

FYI: I tried a rental for 11/27-12/3 9AM-9AM. Full-size with all taxes/fees/etc is $207. With your $30 off, takes you down near the $175 that you listed for some of the others. Still not $145, but that's still great for that holiday period.