If your Colorado group earns more than $25,000 in a year, you need a license from the state to sell anything and solicit donations.
Look under charitable donations-
www.sos.state.co.us/pubs/bingo_raffles/main.htm
The process is pretty short, costs $10 and needs to be renewed each year.
Even if you don't reach the $25,000 mark, you may want to consider reqistering anyway. There have been a number of fraudulent fundraisers in our area that may make it hard to get donations. The most notable is a man who contacted businesses to put together his own coupon book for school fundraising. He took money and items in the guise of trying to help local schools, then pocketed the money and never published anything.
When you type up your donation letter, you would have a reference number from the Secretary of State showing that you are registered and legit.
If you find you accidently go over the limit, and haven't registered, they ask that you register ASAP and it will be effective retroactively.
You also have to get a license for any raffle in Colorado. There needs to be a registered games manager and you have to follow the guidelines for printing raffle tickets. There are more details on the SOS website (above).
An important note about raffles - you MUST hold the raffle if you sell tickets. You cannot give refunds if there isn't enough participation.
This may seem like extra work, but in the end you will have a better raffle because you have someone trained to run it. The registration to raise funds may just give you another in for looking more organized and responcible. I like that sort of thing myself.
I hope that helps someone.