Spend the money up front for a good one or make your own. I made mine for a bout that price and it mixes like a champion on steroids.
Research or ask questions here. Almost everything you need can be purchased at radio shack or Amazon.
Great videos on YouTube. But the guys making beer don’t need the power and magnetic strength we do. If your interested I could probably pull up my old notes and radio shack part numbers.
All you need off top of my head is
Project box (you can make on from work. Mines aluminum) could be plastic
12v computer fan
Plug for wall I have 6v, 8v, 12v wall adapter
Rare earth magnets
On off switch
Small gauge wire
Soldering gun, (optional)
Bolts for fan to box
I can shoot some pictures for wire diagram.