I am in charge of planning my friend's bachelorette party in Aspen. Does anybody have any suggestions for active and lower-cost things to do in the end of May?

you might include a ride in www.ultimatetaxi.com

Have you searched an Aspen tourism website? There might be good music concerts some evenings, even that early in the season. What about a wild white-water raft trip?

I'm not an expert on Bachelorette parties (or women in general), but low cost and Aspen usually aren't used in the same sentence. The Ultimate taxi is a good recommendation. He can take 5-6 people (depending on size) I think it's a little over $100 and includes some neat swag. If it's in your budget, stay at the Sky Hotel. It's definitely cool and has one of the best bars in Aspen, 39 Degrees, on premises. Kind of pricey though. It would also help if you could say when you're planning to go.

Thanks everyone for the replies. I did book a room at the Sky Hotel on your advice and I'm also contacting an old friend who does whitewater rafting in Glenwood Springs. Thanks for the advice!