You oughta be signed up on Joanne's and Michael's mailing list as they are the main distributors of Wilton products. I pretty much don't buy any cake decorating item unless I have at least a 40% off coupon.
And just FYI...if ever you are ever emailed a coupon from Joanne's or Michaels, you can print out 2 copies and use one at each store.
Here's what I do to maximize my coupon use: I use one of the printed off coupons at Michael's. Most of the time they give me another 40% coupon with my receipt (Joanne's doesn't give out any coupons with the receipt). I then take the coupon I have just received from Michael's and the other copy of the coupon I got in my email and go to Joanne's to use them. Saves me lots of $$!