Doing research on this issue myself, it seems that certain title companies do not do dry funded double closes because they are uncomfortable with performing such transactions.

The calculator is free, it's accurate as long as you know what numbers to plug in, and it helps you think about line items you might forget to include, like closing costs, which can impact how much cash you walk away with.

The best source for accurate and real-time rental data is NARPM.

What you need to know is how much work you can perform without needing a permit. 

An income based approach can be part of what an appraiser takes into consideration for value, though the potential income an appraiser might use is a very conservative average based on broad data, not the individual cabin's past performance.  

This includes the fact that contracting to purchase a property of which you do not have ability or intent to perform on contract is illegal in a great many areas of the country, and yes people DO get prosecuted on this every year. 

@Mateusz Sokol you are out the transaction costs because an appraiser already performed their services.

A lot of posters here keep saying sue for specific performance, but that happens about 0.000001% of the time.Think I'd take my inspection fees and get my E/M back and learn that you really can't force a seller to sign.And even if you could, a signature under duress isn't legal often.

(b) (1) Except as provided in paragraph (2), this division shall not apply to a depository institution, as defined in Section 1420, a person licensed pursuant to Division 9 (commencing with Section 22000) or Division 20 (commencing with Section 50000), a person licensed pursuant to Part 1 (commencing with Section 10000) of Division 4 of the Business and Professions Code, a person who is subject to the Karnette Rental-Purchase Act (Title 2.96 (commencing with Section 1812.620) of Part 4 of Division 3 of the Civil Code), or a trustee performing acts in connection with a nonjudicial foreclosure pursuant to Article 1 (commencing with Section 2920) of Chapter 2 of Title 14 of Part 4 of Division 3 of the Civil Code.

You need to know the markets numbers and demand to price your places accurately and therefore make them profitable.