We use Big Train for ours, but the principal behind the drinks remains the same. Unfortunately, we have found that these drinks do have a high cost relative to other drinks that we make, especially espresso-based drinks. There might be a few alternatives that you could look at, including:
(1) Could you use less of the frappe base? What I mean by this is, could you use less of the Cool Cap but still retain the same good flavor of the finished drink? This is subjective in nature, and would take some experimenting on your part, and it may not make that much difference in the bottom line of the drink cost anyway.
(2) Could you raise the price of your drinks? This again would involve some work on your part, to check out your competitors who have similar products and their prices. Are you priced competitively? Are you under the prices of all of your competitors? Are the margins that you make on this drink comparable or better than your espresso-based drinks, or worse?
(3) What about offering different sizes? Sometimes places will offer smaller sizes, but the retail prices don't go down that much. If you have a lot of people who would like to have a smaller size, this might be a way to increase your overall profits. This again has potential pitfalls, like obtaining new sized glasses if you don't already have them, etc..
(4) A final idea would be to look for a new supplier for the various ingrediants of the drink. Can you purchase the Cool Cap base cheaper from a different vendor? What about the other components, like ice. Can this be obtained at a more competitive price elsewhere? I will not suggest compromising quality for saving a few pennies, but sometimes you can legitimately save money by looking at different suppliers of the same product.
Hopefully others will have more ways for you to potentially reduce your product costs. Good luck!