Don't forget to factor in your time. Time is a pretty valuable commodity. You'll spend a good amount of time cleaning, watering, checking temps, etc... Once breeding season comes around you'll be even busier.
I'm not saying you are but if you are going into this solely based on making money then my advice is don't. You really have to enjoy this hobby to make any money from it. I've made money breeding but enjoy it way more when there's not so much pressure.