You have to buy the Wally Course AND a Sinker kit. If you also want pregates you need those kits as well.
Full Wally sinker system with pregates requires the following
Kit 1 $2,233.75
Kit 1a $521.50
Kit 2 $2,505.00
Kit 2a $455.25
Total price = $5,715.50
If you get just Kit 1 and Kit 1a you will have a fully functional course that requires leaving up or submerging manually.
I know this since I am trying to justify upgrading our Wally course to a Wally sinker by adding kit 2 and kit 2a. We currently submerge manually on our lake by removing the buoys.
https://shop.wallyskier.com/WallySkier-kits_c4.htm
Also you need to buy your own PVC pipe locally and make 2 anchors yourself.