@Eric Berkner  Depending on the other rents in your market and whether other owners in the area are billing for gas, will determine how much you can charge for it. 

I looked at enough properties though to determine my money would be better spent on other amenities. 

Lastly, if by "calculating", you mean performing a financial analysis to determine projected income, the answer is no it is not more difficult to calculate.

They clearly want to grow into a higher-end accounting system so even their desktop version requires you connect to the internet. 

Trying to determine future appreciation, inflation, rent increase, tax depreciation, etc. becomes a bit nonsensical and is well outside of my wheelhouse. 

All you need is an internet connection and a good team

I know the intelligent investors here can help me far more than any internet search.  

In 90 - 120 days business owners can obtain $100k to $250k in unsecured business lines of credit themselves.Follow these simple steps:1) Establish a strong internet presence for your company by listing it on at least 15 sites-- Facebook, LinkedIn, Twitter, Scoop It, Bing, Manta, 411, Google+, Google Places, etc.2) Establish a business checking account at 2 banks (with a 700 credit each will offer a business credit card.3) Make regular deposits into your business checking account for 90 days to establish a favorable bank rating.4) Add higher level trade references to Dun and Bradstreet to provide depth to your Paydex Score (net 30s are usually lower amounts; you'll need higher approvals from your trade references-- 2k to 4k).5) Upload your company financials to Dun and Bradstreet to complete your file and create a strong credit profile.6) After 90 days apply for unsecured lines of credit.

Pulled up the internet and it was one of the first houses we saw.

The amount of things that can go wrong are too many to count, especially when you have unknown unknownsI think whether you are doing it yourself or not should be determined by the size of the project.