Lucky you! I'd go crazy in a store like that.
When I buy boxes of Lipton's Onion Soup mix, they usually have a free packet of their Ranch Dressing Mix. I don't keep buttermilk around, but I mixed a packet in with a pint of sour cream, and it made a killer dip! You could have easily used it as a salad dressing.
For creamy homemade salad dressings, I generally start with Miracle Whip Lite. You might give it a try...it has a nice tangy taste. I usually thin it with just a little milk until it's the consistancy I like.
We get by with a little help from our friends