With so many Realtors listing everything on Zillow or realtor dot com, you can bypass the MLS. I have a lot of fringe areas where there is spotty or overlapping coverage with other MLS's.
So this is my procedure. I am in a disclosure state (s).
a- I have access to all counties in the region via vendors who produce searchable county assessor field card databases. They are frequently updated (some counties literally daily) and I find all the sales in the area I am working. From that list I start plugging in addresses in Google
b- Once it pops up, there is usually a link to a realtor dot com or zillow page. I pull that up. Once I have that information, I can usually find the agent or broker. Call for any info I need. Since our local MLS won't report concessions, financing, etc. you can often get it directly from the agent. When you can't then the next stage is...
c-I have access to deeds and mortgages via one pay site in OK and free in several counties in AR. I think search the buyers name. I look at the mortgage. At the bottom of the 1st page of the mortgage will be whether it is FHA or GSE, or if nothing, it's in house. There may be a second mortgage held by the seller in some cases (and I bet your MLS and agent didn't mention that if so) and you will find that, too. If no mortgage, it is either cash or financed by using other property as collateral...cash anyway. And the mortgages here normally state the amount lent (since they have to pay a fee based on price) So, then you have the list price (z & reltor have history of listings, DOM, etc.) you usually can tell if a significant concession was made (again, the agent normally will tell you.)
d-While FNMA might require you be an MLS member, there is nothing in USPAP requiring it. I find that I can pull up the above as readily as I can rely upon the MLS. Too many times in the MLS, I found Realist was not up to date while both the courthouse and the county assessor records were. This is especially true if the sale is less than 30 days old. Even with the MLS, I will always pull up the county assessor records AND the deed and mortgage even if it means going to the courthouse clerk's office (which a few very counties in my state may still not be on-line)... and how many appraisers today have ever sit foot in the courthouse?