Cash flow is king and saves you from the lumpiness of doing all cash flips. This is one of the cleanest ways to build it. Here is an example. You buy a property on terms from a motivated seller. Say $50,000 purchase price, $5,000 down, $500 a month for 10 years. You then sell that same property to an end buyer on terms like $80,000 sale price, $10,000 down, $800 a month. You get paid $5,000 at acquisition and create a $300/month cash flow spread. Make sure your underlying note allows for early payoff without penalty, and confirm there is no due-on-sale clause in your purchase agreement. Some sellers will not do this, but most will. If the Seller wants interest, try stepping it up over time (i.e. 1% year 1, 2% year 2, etc.) so as the interest rate increases, you're paying it on a lower principal amount. Get 20 of these running and you've got a nice steady stream of income.

@James Gross - Love seeing the reverse engineering of an outcome. The assumptions are mostly solid. Might tweak the close rate a little. We see 30-40% of contracts fall out for one reason or another. Bad perc tests, title issues, sellers who get cold feet. If you want certainty of 5 closed deals, aim for 8 to 10 contracts. Your $20K spread assumption is solid for rural parcels in the $40-80K range. One tip: track every fallout and why. That data is worth more than any marketing tactic.