après in Aspen is oysters, fine wine, and white table cloths.
I think you're not looking hard enough... Snowmass Mall has some pretty casual and drink-focused places, and Aspen has some restaurant bar or brewery places that are much more laid back.
There's plenty of snooty/high end stuff of course, but you can find other options. Nothing may be "cheap" depending on your frame of reference (mine's the DC area, so maybe skewed) but there is some variety.
Personally, I also thought it was fun/interesting to hang out for après at the patio at Ajax Tavern, as people ran the gamut from those in furs and fancier ski outfits (who were probably the "white table cloth" crowd), to a bunch of us Ski Talkers, to a few ski-bums, to some younger locals and families. It's just a patio and very casual, and you can watch people coming down the slopes.