fluorescent tubes would probably be your best bet...i'm sure they are available in lengths around 2 ft. a mixture of 3:1 cool white to warm white will make for a nice complete spectrum.

avoid the bulbs that say they are for plants and stick with the regular cool and warm white as they have always seemed to work better to me

for lower light plants (most herbs and wheatgrass) you can get away with about 20-30W per square foot of lighting, so in your space (about 4 sq ft) you wold be best to have 120W or so of lighting. ..so 4 30W tubes or 3 40W tubes should do it nicely. hope this helps!

You should look at compact fluorescents, 2-D fluorescents, and the various bent/looped fluorescents. It is quite easy to find nice hi-power compact fluorescents now and they are ideal for lighting a small area. You can get short straight fluorescent tubes but I find them to be nearly as expensive as the long ones and hard to find in high powers, so then you need a lot of them.