I purchased my Greetings Stamp set at Hobby Lobby. If you have a Hobby Lobby nearby the stamp sets are on sale this week 40% off. Just in case you find something that's not on sale I've included a link to their weekly 40% off coupon, this coupon expires Aug. 4th. I hope you found this helpful and have a happy and crafty day!
Update: I was shopping at Hobby Lobby on Friday, Aug. 3, 2012 and I found this stamp set on clearance. It may not be around much longer. However, I've also seen it in stock at Jo-Ann Fabric and Craft stores.