Most of the properties are lower 600's and rents range from 2500 - 2800$.

In smaller cities the top notch properties will be in the 6 range. 

Then if the market value all falls into the same range then you can confidently move forward with an appraisal at your own expense.  

And one last thing that hasn't been mentioned yet is that most mini splits aren't ideal/appropriate for heating in extremely low (below somewhere around 20F) temperatures, the specs will all list the temperature range.

I currently do not own a primary residence, but would be looking to buy one in the ~700k range in the next 1.5 - 2 years.

I have started my search for good location in Florida to invest in short term/vacation rental in 300-400 price range.

Once you have a bit of knowledge under your belt, start looking at your local area and just watch the real estate market and see whats happening...see how houses are being sold, how quickly, what price ranges, what you are getting for that price range, etc.

We're relatively new to this and seeking our first STR property in about the $500K range using one of those 10% down loans and the cash from the original refi we did at 70% LTV. 

Look at your comps and stay in that range of renovation unless you can outdo your competition without breaking the bank.2.

Would likely start with something in the $100-200k range (LOC ready to go) and I'm assuming a smaller detached house is the way to go?