Birthday Invitations from Shutterfly

I've been using Shutterfly to create birthday invitations for my sons' birthdays. And each time I order, I end up only having to pay tax and shipping (around $6-$7 total), thanks to coupons/promotional codes that I've been collecting! These are on the way to me (hopefully they get here before Thanksgiving so I can pass them out to family next week).

Where do I get these promotional codes from? Well I had one for $20 off any order of $20 or more from Similac; also a couple from when Pampers had these coupon booklets in the boxes of diapers a few months ago, I received some coupon codes in the mail this week and their website often has discount codes as well. I'm not endorsing Shutterfly or anything, but their cards are pretty cute and there are awesome deals there!