I built a light fixture today with 16 CFL bulbs in a straight line 8 feet long. It's a lot of light, but I may need two.
Costco has a good price on 23W 1600 lumen CFLs (about $8.00), but there were some rebates that knocked another $2.00 off the price. So each box of 4 costs $5.99 right now. I was going to use T5 bulbs, but I saw that, and did the math.
I'm waiting for a response from the manufacture for more information about the light spectrum. All I have been able to find so far is that they are "Full Spectrum". I'm hoping this will work for me, if not Costco will take them back.
I'll post a picture of my finished grow lamp after it's painted, and the specs if I hear back from Feit Electric.
Here are the specs on the CFLs that Devin Duhaime is using very successfully.
Philips 41409-4 - 26 Watt - CFL
100 W Equal - 5000K Full Spectrum - 82 CRI - 114 Lumens per Watt - 15 Month Warranty