One contractor claims he can finish the job in a day with three workers, while others estimate it will take a week.I'm not sure how to proceed with this situation.

I have had a couple of estimates to complete this work and it ranges anywhere from 40k to 75k.

@Joe Jor brings up some great points and I like his suggestion for contacting the building dept.You may also be able to negotiate credits or for funds to be held in escrow - until seller removes open permits, violations, etc.Lastly, for estimates on the work that will need to be completed on the property, you could also contact an expeditor who services Westchester.All the best to you on your search!

I estimated a conservative 75% occupancy on my current house hack but stay nearly fulled booked out.

That way you're not locked into the deal without getting an estimate and if the rehab budget comes in higher than $65k you can easily walk away- make sure the assignment says EMD is refundable if you do decide to walk.The 70% rule is a great rule of thumb.

Cash Purchase Price: $43k, Renovation & other fees: $66k, Estimated closing: $13k.

The property owners will be asking $170k, but it needs an estimated $60-80k in repairs.

I would t go much lower unless you can estimate rehabbing accurately or bear in mind the asset class to vacancy and other variable cost issues rising.

Does anyone have rule of thumb cost estimates for this kind of work?

This not only lets your get a discount when these suppliers compete against each other, but if you have detailed plans from an architect or a spec for the build out - they can also estimate all the materials needed for you.