They pay for themselves and put money in my pocket to build up a reserve for the next purchase.

For each property, I have a few accounts including a high interest earning savings account for reserves within the platform.

Our privately owned and centrally controlled monetary system, known as the Federal Reserve, and the legality of Fractional Reserve Banking is on a crash course for a battle between Freedom (Property Owners) and Royalty (the banks). 

For me as well as the seller.First, you have to define Sub to financing.Do you mean the reckless kind where you overpay for a property, take over the financing and borrow from others to cover closing costs and holding costs when you have no money, no credit, no income, no reserves and can't tell a warranty deed from a deed of trust and you close on the kitchen counteror do you meanbuying below market value, already having a nice income, having reserves, using escrow and title, already understanding the due on sale clause, have done a lot of creative purchases and know when to use and when not to use creative finance and how to recover if something goes amiss?

You said, "I'll have to put in extra of my own money for reserves..."

While very lucrative - if you don't have enough reserves, it can really break the bank. 

Even OO with closing and reserves it will not go far.

If mixed in with your deposits and reserve funds, you may accidentally spend money you shouldn't have.

The down fall is a Heloc can "Never" be used as an asset or for PITI reserves required when buying a new Primary or investment property.A heloc can also cause major issues with credit and one slight hiccup or missed payment the bank or lender who is holding the Heloc can close or reduce your line of credit.

I’m curious how you all store savings for things like reserves, CAPEX, etc.