Actually, if it is expensive enough it only needs to sell to 10 DMs in each city to make the same profit as a book that sells to 40+ people in each city.
Anyhow, I voted yes. $65+ is fine. Of course, with the caveat that it is well done. If it were simply to be a 300 page dungeon crawl with little rhyme or reason and no continuing motivation for the PCs once they are underground then I wouldn't go near it. But if it were a matrix of mini-adventures that were connected by a variety of plots and events so that the players are not railroaded, but the motivations and goals are still clear, then I would probably go out of my way to pick it up.
Of course, the more stuff that is included the more I would be willing to pay. Counters are fine, but I've got lots of minis so they aren't really essential. Player handouts are more important to me. Not just pictures but background information on the region/city/location is something that I really like -- information that is designed with the player in mind, so it hints at the secrets but doesn't give them away, while immersing the player in the millieu. Players' maps, keyed for commonly known information not for encounters. If a PC is from the area, they'll know where the Baron's castle is without asking -- having a map with the baron's casle clearly labled will remind them that they know this and that the castle is right next to the graveyard where the noises have been heard. I don't have to lead them by the nose as much by pointing these sorts of relationships out when they have their own detailed map.
A detailed timeline would be good. 20 levels is going to take more than a few months of game time, so the world is going to change. Having a list of these changes with the "modules" or "scenarios" explicitly altered based on how early or late the PCs get to that section would be fabulous. e.g. the Sorceror Henchman is level 7 (insert statblock), level 8 after 13 June, 1287CE (insert statblock), level 9 after 2nd February 1289CE (insert statblock), etc. Make the adventure dynamic so if the PCs decide to take 6 months off to craft magic items around level 12 then it is going to have some effect on what happens afterwards.
Tiles? If they are throwing in counters as value added material and the price is already through the roof give me 1-inch gridded floorplans of some of the larger or key rooms or locales so I don't have to take 5 minutes before the encounter begins to describe the room and draw it on the plexiglass . If there were one or two locations per level (i.e. around 30 locations) it would be great. These don't have to be colour, but if it fits the economics I won't complain.
Don't make it too generic. It doesn't have to fit into my homebrewed campaign. The box takes the players through 20 levels so it is a self contained campaign. If I wanted to run my homebrewed campaign I wouldn't be running this box so make it unique and interesting. Now here's the Tall Order: don't make it too unique either. It has to be generic enough that it will sustain my players' (and my) interest once the novelty wears off. I don't want a two year campaign where there are no elves and dwarves, only humans and gnomes (for example).
Just my two cents. I'm sure we all have our own wishlist, but if the quality were high then I would be willing to pay quite a bit for something like this. (But give me some warning so I can save up my disposable income.)
Cheers