They find deals on oceanfront houses all over the country.I'd even look for a fixer upper to get a great deal.

The property sat on the market for a month before an offer came in, but the buyer backed out at closing.

Since you estimate a resale value of $200-215K and renovation costs of $60-70K (although you said that's on the higher end), your margin is tight, especially considering closing costs, realtor fees, and unexpected expenses.

I was a Realtor when I purchased it in 2019 and I used my commission towards the closing costs and I am a U.S.

Buy: $284,900Rehab: $115,000Holding: $16,500 Points: $3,413 Selling fee: $30,000Insurance hold: $2,000-$2,500 (maybe get back $1,000-$1500 if you close quick)Other title/escrow purchase: $2,500ARV: $500,000Profit: $46,587 (9.25% approx) I would do the deal, especially if you get that gap for rehab closed 3-4 months and tighten up the rehab costs too ($100,000)   

Is the ATR still a relevant indicator of a deal?

Once you find this range you should be very close to understanding your buy box. 

If everything checks out, they could be a solid option for your first investment deal.

Hey,I am curious if any of you have found good deals on the market that were listed on the MLS for a long time (90+ days). 

This is not even close to the documents required for a properly drafted loan.