Your mileage may vary!

But I'm sure the cost to build doesn't vary too much from county to county (as opposed to cost of land). 

They are costing you money you do not have...if you are not prepared to get rid of them your priorities are completely scr**ed up. 

There's no mortgage and net annual income varies between $20,000 and $30,000.I've recently been reading up more on real estate investing and I feel like my capitalization is really low.

@Albert D.As a civil engineer, I see a lot of these costs for my projects, and they vary greatly depending on the volume of the project, the area, the type of pavement, if its a general contractor or individual small contractors and you manage them, type of facility (Governmental, individual--private owners--you in this case--, commercial, industrial, etc.,, parking lots, rural roadways, highways, tollways, airfields, etc.)  

The levels of professionalism can vary a lot.

Not necessarily and would vary greatly by market. 

Some will vary to 75% or so but that's the basic numbers in it's simplest form.  

You will get so may varying opinions pro and con that it may become difficult for you to move forward.  

That may be ok if you're trying to understand or learn a new market, but when it comes to analyzing actual properties, things like vacancies, maintenance, cap ex, rent, etc. will vary greatly, even if they are in the same city or zip code.Yes, it takes more time to look up and input actual numbers, but your cash flow projections will be much more accurate and you may actually find good deals that other people