Do you want this thing to be the tipping point for them to leave and you have turnover costs and a vacant unit? 

For me as well as the seller.First, you have to define Sub to financing.Do you mean the reckless kind where you overpay for a property, take over the financing and borrow from others to cover closing costs and holding costs when you have no money, no credit, no income, no reserves and can't tell a warranty deed from a deed of trust and you close on the kitchen counteror do you meanbuying below market value, already having a nice income, having reserves, using escrow and title, already understanding the due on sale clause, have done a lot of creative purchases and know when to use and when not to use creative finance and how to recover if something goes amiss?

Id keep looking if it was not an approved short sale ( even an approved short sale takes a very very long time and theres no guarantee that you will even close on the house after months of waiting). q1)There are plenty of non traditional lenders that could offer you construction financing if the numbers make sense but it will cost you with points and a higher rate.

Every project needs a quote and you should be able to estimate the material costs.

Many who want to scale  fail to take this into consideration,  take on too many projects at once, have no capital to advance the construction and ultimately get stuck in mud unable to advance any of their projects.

To estimate expenses, consider setting aside a percentage for management fees, plus costs for cleaning and utilities.

Your net gain is your net sale, minus your adjust cost basis.

However, that can get costly quickly and slow things down.

Coincidentally, I had this exact same question when renewing our local STR license as they've moved to a system (unfortunately) where the cost of the license is based on the number of bedrooms.

Typically, we see anywhere from $600 to over $1000 per unit (maintenance and turn costs)  depending on these factors.