To make it simple…the investor is trying to buy your property Sub2 and needs you to refinance it into a long-term loan First.The investor does not have to ask the bank’s permission.

One suggestion to consider as I mainly do BRRRRs as well- find a local bank or credit union in the area you plan to buy that offers construction loans.

These days I can't buy a lot for $40-50k.

Some knucklehead watched a YouTube video, where they "teach you to be rich by buying businesses with 100% seller financing." 

I have found that Redfin actually has pretty good search parameters to where you can look for listings that have been sitting a while that fit your buy box, and you can even do keyword searches for things like "as is", "investor", "seller financing", "guest house", etc. depending on what you are looking for.

I’d also look into using an FHA 203k renovation loan, allowing me to buy something unqualified for a standard mortgage, which would weed out a lot of competition and push the price lower.

I had not thought of that since I am not buying or selling anything.  

I am under contract to buy and flip a house that I am paying $615K for. 

@Camille Romero I would not buy a property in a city with a declining population.

I buy in OKC and Birmingham for rentals.