I am new to growing, ummmm tomatoes, but I do know a little about growing orchids and other specialty plants. Orchids are generally grown in medium that will drain too fast for your plants. If I were you, I would make your own by using organic(no nute) potting soil, then mix perilite, vermiculite, turface, etc. to help loosen it up.
FYI - Turface is an excellent soil conditioner. Cheap, porous, etc. 50lb bag was about 8 bucks. They use it on baseball fields and readily available. I plan on substituting it in place of perilite and/or vermiculite.
I have heard of people using 50% soil, 25% perilite and 25% vermiculite. Good luck!