HELOC---------------My husband job slowly progressed, and as a physician our disposable income increased.This Boston condo bought us 1. 20% down-payment on our Live in Flip (2006)2. 20% down-payment on our very 1st commercial unit, (NNN lease) (2007)3. 20% down-payment on my current primary home in pittsburgh (2010)4.

Keep us informed of your progress!

Three of those have required about 30% upfront and the last one I was able to negotiate a 20% upfront and 40% upon full finishing with a payment in the middle at 75% progress which I decide fairly "liberally".Like any contractor, I had my issues with quality and timing but the retention of  funds always made the discussion cordial and allowed me to reach good resolution.I can provide a couple of contacts offline.

I'm assuming that these properties are in the path of progress and upward mobility hence you should factor in some appreciation as well.

Keep pushing through the times when it seems like everything you do isn't getting you any progress.

:D I am excited with the people i have talked to and look forward to progressing further.I would appreciate any suggestions or info you may have to offer, and what options you may have. 

Since you expressed an interest in flips, I added the link below for your reading pleasure.http://www.biggerpockets.com/renewsblog/2014/01/07/flipping-houses/ (step by step guide to flips)To be more successful, you simply have to work on the other elements to progress your REI pursuit.

That might be worth it if the property is in the path of progress and likely to become more valuable.

@John Wulf if your goal is to accumulate enough cash flowing rentals for early retirement, paying off houses is going to slow your progress.

To be more successful, you simply have to work on the other elements to progress your REI pursuit.