From this data, you can utilize a website bestplaces.net that will give you a breakdown of the percentage of homes that sold, in various price ranges, for a given zip code.

If you are concerned with the Due on Sale, don't transfer, have a delayed settlement for a few years or until you are ready to flip the deal; just make sure you have a good lien and title report and have the seller's deed signed and held by you, your lawyer or a title company.

There are usually many times when there are no new listings in my area, so random checking throughout the year tends to give me better overall data than just waiting until it's coming vacant.  

I'll have to take out the investment loan on my own person for now and then figure out a way to transfer the title to the LLC (not sure if this is done during initial contract, or if I just need to pay for title/search-type fees later and transfer it to the LLC).  

There are some counties that you will need to go to the tax deed application site in order to see that it has been transferred into your name as the tax lien certificate holder. 

The deed doesn't transfer until the contract has been paid in full so it doesn't seem like there is much risk of due on sale clause.

Podia can act as a database for these properties.Even Zillow had a notes section you can stored unstructured data in but can't search it, etc

I reached out to someone today who sent me a letter and he would like to buy it subject to.There is a loan of $185,000 on the property in my personal name with Wells Fargo.Total rents are $3,010 a month and the mortgage payment, including mortgage interest, taxes and insurance is slightly over $1,800.He proposed paying me $10,000, taking care of my listing agent and paying all transfer taxes.We would transfer the deed into a trust that he is the trustee of, sign an agreement that if he missed three payments the property would come back to me and an agreement for him to sell or refinance within 5 years.The guy was calling from addicted2realestate.comAssuming I couldn't net more than that by keeping it listed, where is the risk and downside to me?

If you would like more market data or if I can assist you in any way feel free to contact me. 

Find out why seller is selling, ask for a rent roll, what repairs or updating of mechanicals and roof has been done, how long seller has owned the property, are there pets allowed, are taxes current, has there been any insurance claims where seller did not use money for the repairs, ask for sellers disclosure, are there separate water and electric meters, does rent include utilities or not, are there long term leases or month to month, does deposits transfer to new owner, if there is pets, is the deposit a fee or deposit.