Nice stealth space I did the same thing when I started tons of research.
TO MAINTAIN BUDGET I WOULD:
1. Use CFLs for lighting
2. For ventilation I would cut a hole on the bottom of one side and a hole in the top of the other side and install cpu fans on the inside of the cabinet over the holes. Bottom hole being air in and top hole being air out.
3. odor Control Within budget would be to tape a dryer sheet over the exaughst hole
4. Use soil as a medium
5. Get a digital thermometer
6. The most important keep researching and learning.