At $22 for a professionally built one, why would you want to build your own? Are you going to "reinvent the wheel" or do you just want to start and fly your airplane?
Last time I checked this was a Hobby and building your own stuff was still part of it.....I love building my own support equipment because I CAN! Even if it cost twice as much as the "$22 Professionally built one", i have the pride in knowing that "I" built it and configured it to my specifications. Building stuff like this also enhances your skills at doing other hobby related things like scratch building or repairs.....dont discourage.....encourage!
CB