In just a few weeks things will start heating up here in the Northwoods and it will be time to start thinking about planting seeds. A greenhouse is a great way to start those plants earlier than you could normally. The article above gives step by step instructions and photos on how to build your own greenhouse for very little money.
If you want a more permanent solution you might also look at the local vendor Harbor Freight Tools in Saint Paul. Their aluminum greenhouses are from $300 to $700.