Have you ever been out to ski/snowboard in Colorado before? I would probably shy away from the Aspen resorts because not only will the skiing be expensive, so will the nearby lodging and restaurants. Any of the resorts along the I-70 corridor are going to run about $100/day for lift ticket prices unless you buy multi day passes. You also may get better deals with a lift ticket and lodging combo package. Are you going to be renting a car or taking a shuttle from the airport? If you rent a car, I'd suggest getting a hotel room in the middle of Summit county away from the resort hotels to save some cash. Then you could also drive to different resorts for some variety. If you plan on taking a shuttle and want to stay in a hotel at the base of a resort, I'd suggest looking at Vail. If you are going to stay at one resort for the whole trip, Vail is a good resort to pick because it is so large with a wide array of terrain.
The resorts in Summit county and the neighboring Vail Valley include: A-Basin, Beaver Creek, Breckenridge, Copper Mountain, Keystone, and Vail. Loveland is nearby as well. Both Breckenridge and Keystone can get pretty crowded with tourists, though there are places to avoid the crowds if you know where to look and have the skills for the terrain. I usually spend most of my time at Breckenridge and Vail.
Another option is to go down to Durango to ski Wolf Creek and Durango Mountain Resort (formerly Purgatory). Those resorts tend to get dumped on with snow, and are not terribly crowded due to their location. That location also makes it a long drive to get to though.
Delivered in Munich, broken in on the Nurburgring.