Wal-Mart, the 42 watt GE bulbs. My area they are $8.00 each, or close to it. They are 2700k in color, ironically also 2700 lumens. If you can afford 6 buy them. You can get the smaller bulbs in 6500k for veg but don't fret about it. Trust me, plenty of folks have grown just fine using just 2700k...