He said he saw the advertisement in the zillow.

The thing I have found is that the buyer client focuses mainly on "lowest rate"...sometimes, they choose a large national lender that advertises on TV, or through their work (military), or some other outlet touting "best in customer service, etc"...In my experience, the large national lenders often slow down the purchase process, or get to a few days before closing and decide that "no, they don't intend to finance the loan because buyer has xyz in their history".  

We found a brand new 3/2 for $299k built with quality materials that rented out for 1850 a month.

It can be a challenge because banks don't want to advertise this product.

Advertise the place available starting November 1st at a higher rate and refer the current tenant to it if they decide they’d like to start renting November 1st.

Im looking for a more detail analysis than this is a 3/2 and mines a 3/2..oh both fully renovated, IMO that’s not good enough.Can anyone suggest any material, a coach, or podcast, anything that would provide some much needed insight on running more accurate comps?!

I have always liked the idea of hosting content creators in our vacation rentals in exchange for some posted content advertising our properties.

See some of Lou Brown's material about finding a buyer first for more reasons why this is a better way to start. 

Do you think the seller could get $199,500 if they advertised it with 2 new AC units?

My experience has been much the same as John's when I openly advertise a listing.