For my ranch I just buy the packets of ranch mix and then mix them with 1 c. mayo and 1/2 c. each cream and water.

For the italian, I buy the italian packets and make them with good olive oil and vinegar.

And the other is a sugar free raspberry vinaigrette that I converted from a recipe on allrecipes.

We don't have Costco here, but I've heard people say it's better than Sam's.