For a terrarium, you could buy a 24" double bulb florescent shop light at any big box home center and get plenty of light. The type of bulbs you use in it would depend on the spectrum you want, but most all would be sold there too, for a lot less in cost than you would find them at any pet shop or nursery.

24" shoplight is perfect. I use the bulbs/tubes that are called daylight deluxe or daylight. Look for the K-rating, usually by the watts and lumens. try to get one that is 6500K. These bulbs have more blue and red light in them then standard soft white and cool white. Although any florescent light will grow plants, the 6500K seem to work best and they definately make the plants appear more vibrant. I also made a very cheap yet functional underhood light for one of my fish tanks. I bought a fan-light kit from Wal-Mart for $2. It had 4 screw in standard type light sockets (cheaper then buying the sockets individually at a hardware store) I removed the light sockets carefully. Where the rivet holes where that held them to the fan-light fixture, I used screws to fasten them to the underside of the tanks canopy. With some extra wire from another DIY project I wired the sockets together. I used an old appliance plug/cord that was lopped off of an old appliance that was discarded. If you aren't a pack rat like me, then an inexpensive extension cord (6' or 12') will work great, just lop off the "female" end, and you should have enough wire to do the whole project ( cost about $2). Use aluminum foil for a reflective backing and you are in business. Oh, I also bought screw in compact fluorescent lights from Wal-Mart, daylight deluxe, 6500K, 25 watt. This gave me 100w of lighting for aquatic plants. Not pretty, but the fixture was hidden by the canopy.

Thanks for the feedback? Are Grolux bulbs still in existence?

Yes, Gro-lux bulbs are still available, but after years of growing terrestrial plants under both plain bright whites and grow bulbs, I came to the conclusion that the cost of the gro bulbs aren't worth it, as the plants grew as well under the cheap bright whites.

I keep two long 125 grow-out tanks set back to back under a 3 X 7 ft X 42" high work table and needed some means to light the tanks while keeping as low a profile as I could get, as the tanks are 24" high, set up on 12" high stands.

We set the work table cross braces to allow free space for four, twin bulb 48 inch shop lamps mounted to the underside of the 3/4" ply we used for the table top base, but I still wanted as much reflection as I could get, so painted the underside gloss white, and used self stick silver mylar over it, on the flat surfaces.

Even with the lights set 6 inches above the surface and needing to penetrate through 2 ft. of water, it resulted in brilliant light and lush growth in plants set in pots on the bottoms of the tanks, and the bulbs are all just cheap, standard bright white's.

However, the tanks do not have glass tops. I use the white plastic grids sold for recessed fluorescent fixtures instead, so there is no barrier between the lights and the water surface.

If you plan to use a glass top on your terrarium, it may affect light penetration: I'm not sure. Hopefully, Woe will come back, as she is more scientifically minded and educated than I am, and could give you a far better assessment regarding that question.

I think they still make grow-lux's, not sure though. As Birdwidow said, they just aren't worth the extra cash because they don't make enough difference then even economy shop lights. The only light that will make your plants grow "better" and is not that much more $ is the GE plant/aquarium(PLAQ)bulbs (or tubes). The only trouble with them is IMO they don't make the plants look as good to the eye. Meaning that the plants don't just appear as nice as with the 6500Ks. The PLAQs give a very pink/orange with slight purple/blue. Great for growing, but not for viewing. I sometimes sneak them in 1 per 3-4 6500K. It still doesn't look as good as straigh 6500Ks. IMO the pinkish hue is annoying. Oh, and Birdwidow, just for the record I am not a she, but a he. Yes, twig and berries, wheels and cannon, etc. etc. etc. LMAO