Looks like they are the Edgar Church or Mile High equivalent for the Men's magazine collectors.
Big difference in valuation though as they seem to range in price from only $15 up to $100 for those Napa copies that are still available for sale. Definitely some pretty spicy and enticing covers there.
I suppose one could make the case given the alleged extent of the trove. From the blurb, I suspect the Napa Collection was cherry-picked long before it was more widely marketed. Perhaps that was an opportunity missed.
Some warehouse finds that popped up on Ebay in the '90's were of similar quality. (See below.)
But there is no strong collector base comparable to comics. Die hard collectors obsessively buy up multiple copies and what one sees on Ebay are typically in VG or lower grade. Hence never very much quality material in circulation at any given time, and it takes great patience to assemble runs. (I gave up long ago.)
The best (i.e.) most lurid covers in nice shape will command a premium but even then I've rarely seen one go past $200.
Original cover artwork does go for big bucks, I am led to believe.
Typically bonkers mad doctor trope (cover by Norm Eastman, who is perhaps the most strongly collected, along with Norman Saunders):
Are you aware of any semi-comprehensive listing of the sweats with artist credits included? http://www.philsp.com/mfi2.html