To your original question, Dave, you're on the right track at first. I'm assuming the $237K is accurate. But, do not divide by 0.9 to get to $263K. That's putting your money in with no return at all. I don't know about you, but I want a return from my money. So, stick with $237K as your maximum price.
Now, subtract off the $20K for work, and you have a $217K max price.
That's not your max offer, its your max price. Start lower if you're going to do some negotiating.
Let me come back to Peter's discussion and tell you where I go from here. I'm borrowing hard money to buy, then refinancing into a perm loan. That reduces my cash out of pocket, but adds a bunch of extra costs. So, if $237K is my calculated number, that's my max permanent loan. I'd subtract off refi costs. I don't buy houses this expensive. They make crummy rentals. So, I'm not sure what it would cost to refi a loan this big. I'll guess at $6K. Now I'm at $231K.
Then I have the hard money costs. So, lets say I can borrow the full $231K. Between points and interest, I'll spend about $23K. So, now I'm down to $208K. Closing costs are makbe $4K. Now I'm at $204K. Now, subtract off that $20K fixup costs. The most I'll pay is $184K.
To go with Peter's approach, and assuming you're buying outright, you have to account for the down payment and actual terms. If you're buying for $237-20K= $217K, and putting 25% down you're putting down $54K and financing $163K (rounded). You also have to put in the closing costs and the $20K fixup costs. Use 20 years and 7% for interest and your actual P&I payment is $1264. Your NOI is $1600 ($1500 plus $100 cash flow). That gives you a DSCR of 1.27. I think that would work, but I've not tried to get a loan like that, opting instead for the proctology exam.
You end up with $336 a month in cash flow, $4,035 a year. You have over $75K invested. That's about a 5% cash on cash return. Uninteresting, IMHO.