If I want to profit 100k/yr, how much would I need to invest?

[John Richardson]

I would want to buy decent-good apartment buildings, nothing that will be a complete headache to manage.  In my area you can find buildings like this at a 1.4% or 1.5 % return on the total investment fairly regularly.  If you are patient and shop around, you reach 1.6% or 1.7%, sometimes higher if you are lucky.  Overall it is a good market to own rentals, not amazing but you can get a decent return.

I am working out of the area where I would want to buy properties and live so I'm not starting in real estate yet.  I'm just saving up as much as possible and will be for the next few years.  

I would be buying at 20% down with a 30 year mortgage on each property I buy.

Obviously there will be a million other factors to consider and at best a rough estimate is all that could be made.  With that being said, how much cold hard cash would I have to invest to reach the goal?