Can I purchase SlackYard parts separately?Updated 5 days ago

No, at this time SlackYard components are not sold separately. 

The SlackYard includes a specific SlackLine made for this setup because other slackline ratchets do not integrate seamlessly onto the anchor.

Technically, they'll work but will have to be adjusted to account for the loop on the ratchet side. Also, because of the height of the A-Frames, it will not work any longer than the 5m that the kit comes with, so you would still be limited to the designated SlackYard length.