One option is to search the outfitters in the area you plan to hunt. I inquired with an outfitter that covers the Little Naches unit and if I remember right he quoted $400. That includes using horses to pack the elk from any established trail...so you would still have to get your elk to a trail. Sounded pretty convenient though because you wouldn't have to book anything in advance, just call after you get something down. Never actually done it though, so might be harder in practice. Hopefully that help.
-Vees