There are short term lenders (2-10 year) where you could refinance without title seasoning requirements and pay off your cash in loan quickly, then refinance again for a better rate with a more traditional 30 year loan.

My credit is good and I have no debt, so I don't anticipate having any issues getting traditional financing. 

Since there aren't other multi-families in the area to compare to, should I use the average price per sq ft instead?

The moral of the story---Single Family Homes are a dream compared to Class C or D apartments.

compared to the big banks to try with first?

Have your realtor (get one if you do not have one) run a CMA (Comparative Market Analysis) to find the Fair Market Value once the property is rent ready.4. 

Greeley may be different in terms of the options there since you can still get cheaper duplexes, etc there compared to the cities further West.

Similar properties nearby but yes, it's definitely not a traditional apartment.

Cash allows you to move quickly whereas traditionally financing can take up to 45 days. 

Typically when I compare this to the initial estimate the estimate was high, but usually not by much (5-800 bucks).