Duplex rental property

[Joe Sheldon]

Found a Duplex for sale by owner, asking $89,000, currently both side are rented with a total of $ 1,045.00 per month income. 2017 taxes $763.00 tax assessment is $42880.00. Zillow estimates the value at $49,199.00. My question, is it common for a owner to inflate the value due to the income it produces?

For the numbers to work I would offer less.