That would be correct.
The inner joint is permanently attached to the drag link and can only be replaced with a new drag link assembly.
The outer joint is on a tie rod end which can be replaced individually. Obviously you wouldn't if you went for a whole assembly.
So you would need that whole assembly if what the shop is telling you is true.
Replacing the drag link isn't too bad if you wanted to diy. Then take it back to the shop to have them align it for you. You can find drag links on ebay for cheaper. ~$140
I can't really help with a tutorial.