So where does the name for this coin set come from?

Deerbourne

The first routine I ever saw with it had the line -- "I'll bet you a drink that you can't tell me where the copper coin is -- my favorite drink is a Scotch and Soda." I don't know whether that is the original patter, but it makes a good story!

I assume it was just a play on the colors of the coins. Such a play was used in 'vodca and OJ' which is the same trick but was much more natural during that brief period when Sac bucks were around.

"Vodka and OJ" would have been called something else if Scotch and Soda had not already existed first under that name.

Yup, it's from the original patter, just like the invisible deck

We often hear of magicians who have built a small fortune by marketing one trick -- Duscheck's Wonderbar, Caveney's Coathangers -- for example.

There was a firefighter in Spring, TX (home of the Spring Animal Hospital -- so now you know where to send your worn out Rocky Raccoons) who paid for his house with Scotch and Soda. He would go over to the local magic shop and buy a dozen or so Scotch and Sodas. Then he would go to the local bar and do the trick. The spectator would not only lose the bet, he would want to know how to do it. So the man would sell him "his personal set" for $100. Then he would go to the next bar.