Not sure about Buffalo.
With respect to an Elk Hunt, you should be able to get yourself a nice 5x5 or 6x6 for $5K or less. Fair-chase out west. I know Arizona is draw only. I believe Colorado has over the tag licenses.
I did a quick search for you. Found a place for $5K, with near 90% success rates on Rifle Bull Elk that are 4x4 - 6x6 up to 320".
http://www.ninemileguestranch.com/hunting.html
Spend some time doing research. Email a bunch of outfitters. Then try to find reviews on your short-list of outfitters, talk to references, etc.
Good Luck!