I don't want to deter you from your dreams and goals but why don't you invest the money you have in your online company and make that grow and more profitable?

Cost segregation fees are for professional service and are fully tax deductible, so the true cost of the study will be lowered depending on your marginal tax rate. 

This is where a new investor comes in to the picture offering to fund and run the rehab entirely taking 50% of the profit when it sells.  

I've bought 35+ deals, no condos yet.I am thinking about creating a condo complex, however, and profiting from those HOA fees. 

All of the normal methods don't seem to produce much return for my dad, and even if he got 100% of the cash flow it would take 7+ years for me to see any profit.

Ideally, he would put up the money for the purchase and rehab costs, I’d run the project and then pay him back plus profit after selling it.

Then I would use that lot to build 4 homes as this business undertaking and hope to have the cost of lots be part of my investment, meaning when one day I sell those new homes, I will subtract lots and cost of building from my sales, so to reduce my eventual tax on the profits.

You would recoup your money in a little under 6 years. after that your house is fully paid off, (saving the 75K) and everything after that is profit.

You can do that but every dollar you take in cash or purchase less than what you sell is interpreted by the IRS as taking profit. 

For flipping sometimes it works in high price neighborhoods and the profits are much better with lower risk.