Recommendations for transportation from DIA --> Copper for 12 people?

Hey, Ski-it. I was hoping someone can help with a recommendation on the most cost effective way for 12 people to get from DEN to Copper. I've looked at rental cars and mountain shuttles. The best I can come up with is two Tahoes and that's like $1000 total for the 5 days we'll be there. Mountain shuttles and charters are more than that. Any help is appreciated.