There is a cost to that and the potential for having to spend more to fix things up.  

My total cost is 40k, can resell at around $130.

EDUCATE YOURSELF - yes, it will take time, but will lead to a selection that better meets your expectations & avoids potentially costly surprises!

EDUCATE YOURSELF - yes, it will take time, but will lead to a selection that better meets your expectations & avoids potentially costly surprises!

A bit pricey if you do only a few flips a year, but I'm going to give it a shot and seems if it's worth the monthly cost. 

Do you understand the added complexity, work involved, and costs? 

While the borrowing costs are higher, I’m exploring strategies where the returns could offset this.

Funny enough, I was going to suggest you move out of SF due to the high cost ;-) I'd suggest going down the SF condo route to start as financing for commercial units is a lot more difficult than residential properties.

Both tenants just moved out.I just got a bid to correct the foundation the right way by the most reputable company I could find (full underpinning, 60+ piers) ~$65k, plus costs of repairing drywall, paint, vacancy, and new flooring.

@Voley Martin Make sure you get updated insurance costs.