We have an older pair from this system: https://www.shoremaster.com/all-products/accessories/boat-lift-accessories/configurations/wheel-caddy/
The idea is interesting: you use the boat lift cradle and motor to engage and disengage the wheels. Works well if you have two people to install your lift.
I believe these are in good condition. Remember that these stay in the water all season, so they only look new once. The aluminum arms are what is valuable and the wheels can be easily cleaned or even replaced if desired.
New systems currently sell for over $1000! (example: https://boatliftwarehouse.com/wheel-caddy/)