"I think that when I buy one to ten tray of inserts (12 x 6-packs, 72 cells per tray) the cost is a little more than 1 cent each. How many LEGO bricks would it take to make a cell? 10-20? Hence $1 to $20 PER CELL?"
But Rick -- when you got done using it for seedlings you could take it all apart and make something else!!