I think you are kinda putting the cart before the horse. Unless you are a builder who can do it at cost, it will take a while to see a return in most markets.
If you already had a property, and owned the land free and clear maybe... however the cost to build is much greater than to just buy. Like @Peter M. said, unless you are a builder that can do it at cost it would be difficult to see how this would be profitable. (For such a small unit.) There are of course people who do it every day but for your first property, it's probably not the best course of action. Most builders are only able to make a profit because they build many homes at once and get materials at a steep discount due to the quantities they order.
It's not like flipping, where the property is there are you are just improving it, you will have many costs such as connecting the property to the local utilities which could be inexpensive but can also be (more likely) crazy expensive, it all depends on the land you purchase and the proximity to current local utilities.
The lure to jump in can be hard to resist, but take your time and find the right property. If it is not available in your local market, research other markets to invest in.
Just my two cents, good Luck!