Buying retail vs wholesale / financing

[Jordan Love]

I wanted to get some professional opinions concerning my recent and future real estate transactions. To give you a brief background, I work at a large mortgage company as a loan officer here in the Dallas area. Given the uncertainty of this industry, I have decided to take my income saved and start investing in rental homes to generate some additional monthly cash flow. I currently have a mortgage on my primary residence, 3 rental homes that generate $4,300/month (net $1,500 rental/month), and a 4th property currently under contract and will close here in a few weeks. All 4 of these properties I have been putting 20% down taken from my personal savings, and will have to start putting 25% down once I get to my 7th purchase per Fannie/Freddie guidelines. My goal is to acquire 10 properties before I turn 30 years old (year and a half away), but wanted some insight on other financing as well as finding other solutions for purchasing properties that are eligble for financing at a discounted price. Are there any banks that will extend a line of credit solely based on yearly income and credit scores? This would be ideal if I could purchase with the line of credit then refinance into a conventional 30 year fix without liquidating my personal savings. All 5 of my recent purchases were scooped up on the first day on the market and I am really just looking for any advice to better compete in this aggressive DFW market.