Looking for a cheaper used one of these:
https://www.amazon.com/gp/product/B0042WGO3Y/ref=as_li_tl?ie=UTF8&tag=trainerroad-20&camp=1789&creative=9325&linkCode=as2&creativeASIN=B0042WGO3Y&linkId=b339a9815122c132fce9f9bc436b0e3d
https://www.amazon.com/gp/product/B0042WGO3Y/ref=as_li_tl?ie=UTF8&tag=trainerroad-20&camp=1789&creative=9325&linkCode=as2&creativeASIN=B0042WGO3Y&linkId=b339a9815122c132fce9f9bc436b0e3d