Hmm, looks like that assortment is not available from Harbor Freight (at least not from the online store). I bought it in a brick-and-mortar store probably a year ago.
I don't think Harbor Freight actually makes these kits.
Looks like these can be found on ebay:
This seller wants $10. I do not think I spent that much when I bought it in the store.
A little searching on ebay or google would probably find a better deal.
Maybe start with