I built mine in 2 days by myself but it is 12x40 so a bit more manageable than a 20ft wide. If you sell the produce you grow you can pay off everything really fast. This first year of my greenhouse produced 250 lbs tomatoes, 71 lbs peppers, 1675 cucumbers, and a couple pounds of tobacco. Most of my cucumbers sold through our co-op for $1/ea which nearly paid for the greenhouse materials. I just put the S9 in but by the halving it will have just made enough to pay for itself.