I have never heard of this $1000 limit and I've gone to 2 sales tax workshops hosted by the Denver Handmade Alliance and some other group I can't remember at the moment.
You will need a state sales tax license and a sales tax license for your county and/or city you do business in. If you do a craft fair outside your city and/or county you will have to pay for a special events license for that location and file a special events license form with the state (free if you already have one for your business location). For example, I am based in Denver so I would have to have a state license as well as the City and County of Denver's sales tax license for all the sales I do in Denver (actual physical Denver NOT the suburbs). I did a craft show at Southglenn mall, so I had to file a special events license with the state (free with the regular license) and then had to file a special events license in the county and city in which the event was located (which I had to pay for just for this event). For that event I would not obtain or file sales taxes for the City and County of Denver since the event was outside the county. Your sales tax you collect will also be different from location to location. The total you would collect in the City and County of Denver is 7.62%, with 2.9% being the state's share, 3.62% being the City and County's share, and the remainder sent to the state for RTD, the cultural district, etc.
I hope that makes sense! Also if you are selling online and you sell to someone in Colorado, collect the sales tax!