The concept of DtG is awesome! It's really powerful selling tool, and great for prototyping larger runs, or showing your clients potential designs for an up-sell.
However, that being said... it's really hard to make any money beyond 1 case of shirts doing it this slow. We tell our clients that beyond 12 shirts it's better to go to screen print. Most people don't want to pay more than $2.00 a shirt, full color. And they usually expect a black premium shirt with white ink at this price too. It's insane to try and justify a $25k printer, and then ask these same people for a minimum of $12 per shirt (which is what you need to make to pay back the machine, cover labor and ink and pretreatment costs on these things)
I am so glad I got out of that side of the printing business... in fact I ran away.