The Woodlot is available for purchase at L10. This is a very important building as you will be using Lumber in many quests, crafts, building constructions and a LOT of lumber is required to run production on your Lumber Mill & Large Lumber Mill
The Woodlot gives lumber (wood) every 2h - increased by enchanting and +1 if you allow a neighbor to harvest it for you.
I would highly recommend purchasing a Large Woodlot - however, while saving up Rubies for that premium building, you should build at least (2) Woodlots and upgrade them to L4 as soon as you're able.
Two L2 Woodlots = 2 Shmoos - 80L every 2h
One L4 Woodlot = 2 Shmoos - 80L every 2h
So the L4 would take up half the space and might be the best way to go. Having multiple woodlots and running them as often as you can, helps tremendously. Even if it's just one L4 and two L2's. Depending on the # of Shmoos and space you have a available
Note 1: A L3 Woodlot is not as efficient as a L2 or L4
Note 2: Upgrading a Woodlot to L4 is pretty cheap!
Important: In order to Upgrade your Woodlot you will need to reach the required Magic Level first. (see table below)