Just a thought after looking at some of the pricey stills for homes..
Someone correct me if they've tried this and it didn't work. I'm thinking your quality or quantity might suffer some, but not substantially to offset cost difference. What about one of those kitchen steamers? Use distilled water. Set it to max water/time. Put the chopped mint in the basket and turn it on. After it's done, let water evaporate and collect the oils from the drip tray. You can pick up those kitchen steamers pretty cheap.