For less than $10.00, you can put the whole thing together in about 30 minutes.
I made it at TechShop! I have a router table / saw at my house, but my shop is cramped and it's tough to deal with 8' 2x4s. Doing it at TechShop made it a breeze to put this together!
Step 1: Route two 3/4" slots in two (2) 2x4s
Cut one of the 2x4s to a length of 3 feet.
Route two slots along the entire length of the 3' 2x4.
On the other 2x4, route two slots about 3 feet from the end.
Step 2: Route a 3/8" slot down the middle of the 3' 2x4
Step 3: Cut "keys", drill holes, and screw on the top and bottom.
Drill two holes in the 8' 2x4 approximately 6" and 30" from the top. Make sure that the holes align with the 3/8" slot that was routed.
Insert the carriage bolts and place a washer on the other end, then attach the star knobs
Cut two 18" long pieces of 2x4 and affix one to the bottom of the 8' 2x4 and the other to the top of the 3' 2x4