With the historic low inventory in the Denver area, owner carry situations are few and far between. Some of the agents here on Trulia have had experience with this. I would contact them to walk you through this. i would say that the last thing to do would be to search on Craigslist. There are many scams out there revolving around owner carry deals like this. You not only need a Realtor to walk you through it but have a good real estate attorney to work up and review the paperwork and transaction. Also, most sellers willing to do owner carry are likely to be just as stringent with their lending requirements as a bank and their rates will most likely be higher. Good success with your move.
Your Castle Realestate
To answer your second question -
Let's say the owner/seller will carry a loan for you at $1500 per month payment. That seller will probably want at least $3000 (deposit plus first payment) up front; and maybe more in case you default on the loan.
If there is a valid reason you can't qualify? Chances are sellers will pass on you too. Talk to a local lender on what steps you need to take to be mortgage ready.