The real reason is because as I was about to pay, I remembered that I should search for a promotional code to enter. I hadn't heard of any deals, but I knew it was worth a shot. Sure enough, I took 30 seconds to look it up and found out they had a 30% deal going on that I didn't know about. I ended up saving us $10!
There are 1000's of coupon codes out there, you just have to know where to look. I like to look at Retail Me Not and Current Codes. If you are a big Amazon shopper, be sure to check these sites out- seems like there are always Amazon codes!