coupon discount on base price of product only

[psldesigns]

Let's say i am selling stationery for $50. In my option drop-down i offer return address printing for $15. I want to offer 20% off just the $50 (base price) not the $65 (which is the $50 + $15). Is there some way to do that?

Thanks.

[Jim]

Unless I a missing something 20% of $50 is $10 so just give them $10 off by a coupon.

[psldesigns]

If only it were that easy. We have thousands of products and would want it to work on all of them, where the base price only is discounted, not the options. If we did it on flat fee we would need a coupon for each dollar value and how would we give all those options out. Just wouldn't work.

Any other ideas or possible workarounds?