If you paid 100% with CASH, but bought it at a 30% discount off its immediate appraisal (THAT'S the secret!)

So do not discount the MLS but in addition, use this site and any local REIA's to find wholesalers and agents in your chosen area.  

There are a tremendous amount of people convinced they can make easy money and get a steal that they shampoo the carpets, mow the lawn and make an easy $25,000.

This means you could leave your family with a tremendous amount of money, rather than whatever is left in your retirement account and still live a comfortable life in the mean time.

I see lots of these people have website claiming they can supply properties at 30%, 40%, or more discount.

What you're "selling" is your position in the purchase contract - nothing more.Sounds to me like what OpenDoor is doing amounts to what the short sale flippers were doing during and after the crash: getting ownership of a property at a discounted price, then reselling it without making capital improvements, even though they use property condition and needed repairs to justify their offer, yet they (attempt to) resell the property without making repairs, as Chris noted in his observations of the comments left by those who have had dealings with them.If a seller is sufficiently motivated, that market can sometimes be easily exploited.Having financial backing can allow them to hold properties for the prescribed "seasoning" periods.

If you can buy a property in cash, you're golden and will likely get a steep discount, we normally get 30-40% off list price.    

If you just discount the increase you'll never lose money the years the market doesn't support increases.I give discounted rent for the month of December.  

@Siyu Zheng - Why did you offer with no contingencies if you are not getting a deep discount?

A third bedroom or second bathroom in one area is a tremendous increase in value but may not be significant in other areas.