I use regular white fluorescent bulbs from a reputable brand. The spectrum produced is pretty broad. If you put enough shop light fixtures close enough to the seedlings, then it doesn't matter all that much what type you use, and basic bulbs are least expensive. I tend to stick to the 4-foot, 40-watt T8s and my seedling starts do great under them.

If you want to be more particular, plant growth is best supplemented with a fairly deep red light (690 - 710 nm wavelength), but human eyes do not pick up that range well at all so it appears very dim to our eyes. And because it is so dim, it is not a popular item at your hardware store!

Lower Kelvin lights should tend to correspond more to the redder spectrum.

Regarding the shop lights, you should consider getting a reputable brand on those as well. When I bought mine years ago, I bought the cheapest ones I could find (and made in China of course), and over half of the ballasts have failed in them. Still, I have about 5 fixtures still working!

This forum on gardenweb delves a lot deeper into lighting:

http://forums.gardenweb.com/forums/lights/