Well, I can speak to dry-mounting a bit...
I bought a Niagara that was dry mounted for either $150 or $200 (I can't remember exactly now). Regardless, this poster normally sells for $700-$1200 at auction so dry mounting clearly tanked its value.
I had it removed from the foam core, remounted properly to linen and then restored. However, when removing it from the foam backing, it was apparently a giant pain in the ass and I lost a lot of paper, including some from the *front* of the poster (not just the back). Also, just the removal from the foam core cost more than the linen-backing and restoration combined.
I think it turned out good, but if you look at the poster off-axis (even on the screen... tilt your screen and look from a low angle) you can see a lot of bright white spots throughout the poster. Those are the places where the front of the poster was damaged and had to be touched up.
If it wasn't this valuable of a poster (or something like the Crab Monsters Mel posted) it would basically be more cost than it is worth. So if you do decide to dry mount your posters, keep in mind you will be deliberately bringing their value to $0.
I would strongly recommend against dry mounting.
My $0.02.