What we do have is the determination and drive to make this successful.  

You will need to give a little bit more info for anyone to determine if this is a good deal.

The rent from my roommate and the second unit of the duplex cover my mortgage, insurance, taxes, maintenance, cap ex, vacancies, heat, electric, water, and internet!

Cap Ex needs to be determined by property age and condition.

You are probably intelligent enough to determine that for yourself.   

If you are new to real estate investing underwriters may not count the rent you receive when determining your debt to income ratio and it may be difficult to get loans.

Granted their commodity in this situation is "knowledge" that is not necessarily good, not any tangible property, but value is determined by the free market, and clearly the free market can support a $40,000.00 price point.

Which in turn means the normal laws of supply and demand (which determine value) are more difficult to apply.

That number is key to determining if this project could be successful.

If not, you need to determine the answers to these questions first before you proceed.