Our estimated ARV will be ~$850k.

AirDNA, Rabbu, Pricelabs all have estimator tools.

Re knowing the market, which is one of the reasons (I've read up on that) you'd want a RE agent, esp if not from the area, which I am not, my agent is from about 2 hours away and as the listing is an existing Airbnb for 3 years, I see the prior numbers, and based on that, reviews, and market data, have made an estimate of what I believe it will make under my ownership.

Now, I need to renovate the estimate (40k-50k loan) to get 260-275K ARV.

I estimate that the expenses should be around 900 a month (Not including the mortgage).

@Helene Goodworth the only advice I'd give is that rents in a market as a whole are not usually the best way to approximate what your specific property would rent for.

Some people even write in estimated cap ex in the calculation.  

His estimate is 2-4 Months.The red flags from me are:1.

😎Everything is included for advanced financial metrics as well, such as IRR, Cap Rates, 5-Year Estimated Values, and more! 

They offer free estimates.