I assume that you are trying to do an conventional loan, like a "Flex 95" from Fannie Mae, if this is the case you are limited to gifts and money you can raise by saving the money. (401k etc)
Roberta indicated that an FHA loan might be a way to go, and I agree. If you will qualify for an FHA that would be the way to go. FHA loans are also easier to get in this martket. FHA would only require you to put down 3% and there are programs in Colorado that will lend you that money with little or no payments if you hit the income requirements.
There is "CHFA " They will lend you 3% (up to 10k) for an FHA or conventional loan in the form of a silent 2nd. What this means is there is a lien on the home, but you dont make any payments until you sell or refinance. The link is for the income and loan max information.
"Auorora Hope" & "CHAC" have programs that work like CHFA.
Del Norte - has a grant & Loan programs up to 10k
Plus Nehemaih & AmeriDream both are still good to use until 2/29/2008 with these programs a "non profit will give you the 3% down, and the seller donates the same amount to them after closing (plus a small transaction fee). These programs are ending due to a FHA guideline change but can be used before 2/29/2008.
FHA even has a $100 down program if you buy a HUD home for the starting bid price.
In any case you have a lot of options that you can look into. A good Real Estate Agent working with a good FHA approved lender should be able to get you into a home with little or no down, with one of these programs.