This is one of the sources that I've loved to have before but not anymore today. While those that have you mentioned are the most popular in the masternodes scene.

The return of having those will take time and I have seen how expensive most of them before. Instead of getting into masternodes, just avail a coin that has a POS feature and have it staked.

Although they are likely similar but it's easier to stake because you don't need  to go through the required amount in setting up a MN.