How is the aero garden? I've seen it advertised for awhile now. I'm thinking it would make a good gift for my dad if it works well. would the 6 pod version grow enough lettuce to keep two people with plenty of lettuce to eat? They eat salad about 5 nights a week. I'm wondering if this thing is really that easy and quick to grow things? Also, how often do you need to replace nutrients and bulbs? What does it actually cost to run this thing?