Todd, it was years ago when I went to MT and back then the BLM office sold unit maps by the number and they were pretty good. Call the BLM or get on their website and they used to send a free brochure that showed map numbers and then you sent in an order form. Maybe you can do this all on-line now..... Allen Taylor......
Regardless of where you buy the maps, make sure to call the BLM and have them send you the entire state's map listing, its a great resource. It basically shows a picture of the whole state and tells you the name of each 1:100,000 map for each area.
The BLM maps are the way to go if you're looking for private, BLM, forest service, and state owned land. Not all topo maps show ownership. These maps have kept me out of trouble a few times when well off the road.
However, these maps aren't the greatest when it comes to topographic detail. I used to go to www.topozone.com , but I recently purchased the National Geographic TOPO software for more detailed features and GPS waypoint info. The 1:100,000 maps in the National Geographic software only shows forest service boundaries, but not BLM or state. Maybe the Delorme version has better ownership detail.
fyi the delorme topoquads cd's i bought a couple years ago do not have ownership info, only usfs boundaries and those can't be trusted because of private in-holdings.