Looking for Reliable Short-Term Investment Calculator

[Anthony Terrones]

Hi BP folks! My wife and I are looking to purchase our 2nd deal ever! We purchased our first back in September 2020 and I'm so excited because my partner in life has finally "caught the RE bug!" We're looking at an off-market duplex that the owner is selling because they are in need of cash for their next purchase (they are wanting to upgrade and purchase a lot of land). They are claiming they receive very good income from one side of the property while the other side will cover the mortgage. 

I'm wondering if anyone who reads this might be able to steer me in the right direction to a tool or site that you believe is reliable and have utilized yourself that can assist by giving a relatively accurate idea of what the short-term rental should provide (i.e. vacancy rates, price points, etc.)? 

Thank you to all who view and those who respond in advance!