App for discount-specific error messages

[sf2000]

Hi all,

Is there an app that would allow us to create a discount-specific error message?

for example, imagine we had code for free shipping for orders over $50, but we also had codefor 20% off product X.

If somebody tried to use the shipping code but only had $30 of stuff in their cart, we could make them get a message that says "Sorry, to use that code, you need at least $50 in your cart".  

But if somebody tried to use the code for 20% off the product, and didn't have product X in their cart, we could make it say "Sorry, to use that code, you need to have Product X in your cart"

I've looked a bit but all my searches come up with like 800 apps, and I haven't found any that can do this (yet)

Thanks!