@Devin Berrian - Fiberglass or Steel isn't really the issue.

At that point, you just opened up 1 or more slots of Fannie Mae financing for new rentals to be bought. 

The only advantage I can see to individual sheds as opposed to self storage steel and masonry buildings is that you can scale slowly, by buying new sheds only as you need them.In every other way, cheap wooden sheds are going to be inferior to a storage building, and that will probably be reflected in the rent you can charge.

@John Steele thank you for the advice and encouragement!!

Building is all steel and was built in 2005.  

I think stainless steel appliances and granite will run their course.

Thanks @Dan Heuschele and @Will Grabert.HVAC guy looked at my panel and I have a few empty slots so he didn't think it would be an issue.  

If the walls continue to come in due to expansion of the ground outside, I'll reinforce the walls  from the inside-out for another $6000 in steel, wood, and labor.

$218http://www.homedepot.com/p/Arrow-Newport-8-ft-x-6-ft-Steel-Shed-NP8667/100119313

Only a few slots left, email me if interested and we'll work out the time & I'll share location.