Try to find something white to line the inside of the cabinet with, and cover most of the openings in the pallets, just leave the bottom slat open on one pallet, and the top slat open on the other to help with airflow. Gotta work with what you've got. If you could find a flourescent light that might help supplement a little light.
Gotta start somewhere, read as much as you can on the subject, upgrade when you get the chance, and keep a journal so you can remember what works and doesnt.
If you're near any kind of shipping hubs, you might be able to score a wooden shipping crate that needs a few repairs, and turn that into a cabinet. Or get more pallets, break them down, and build you a cabinet with the lumber. Good luck!