I know it's not a gardening groupon, but I thought lots of gardeners have cats. I really liked this groupon offer and thought someone else might. 50% off from a very good pet store that offers organic treats and natural non toxic pet toys. It's usually expensive to buy these, so 1/2 off makes it worthwhile. There are a few offers on the page, look for the photo of a dog with a yellow ball.

Here is a link that might be useful: $15 for $30 Worth of Pet Supplies at The Fish & Bone