I would talk to a local realtor or appraiser about "adding value" to your property. In some areas, a shop/outbuilding has to have concrete flooring, heat/air/electric AND plumbing in order to "add value" to your property.
We ran into this issue while living in Oklahoma. We were planning on spending ~$40K putting up a large building (40x60x16 w/5 tall garage doors, people door, and a 16' deep lean-to along the 60' side: DIRT FLOOR AND ELECTRIC ONLY) to store 3 trailers in, that also had horse stalls in it. Thankfully, we talked to an appraiser first, who, during our appraisal, told us we would only get $15K in "added value" if we were to build the shed. Definitely not a good financial decision considering we would be selling the home within 3 years.
The building will most likely increase the "sellability" of your home. Not sure that is even a word - but basically, the building will make your home more attractive to potential buyers. But don't bank on the "added value" until you speak with an appraiser.