My suggestion for staying inexpensively would be to check out vrbo.com (vacation rentals by owner), unless you already have a condo. I'm assuming you're driving, so here's the deal for Summit county... The cheaper places to stay will be Dillon, Frisco, Silverthorne. These are all 10 minutes max from Keystone, Breck, Copper, and A-basin. You'll have to drive to the resort everyday, and will need a taxi or DD for getting home if you want to go out, and I would go out in Breck. You can also drive to Vail or the Beav in about 25-30. But if you stay in these places, don't plan on going out at night in Vail, you'll have to drive Vail pass. If you want to be closer to Vail, Avon would be the less expensive place to be, and is where Beaver Creek is too. Nightlife is best in Breck or Vail.
Although it's smaller, and a further drive from Denver, Crested Butte is also a great little town. You can stay there or Mt. Crested Butte (the resort, yes they are two separate towns, it's kind of weird), but I've always had a lot of fun there, and they have some great bars. That being said, CB is a much harder mountain than Breck.