I saved $216.50 with just the 50% off back to school grocery coupon. I bought a ton of organic products, almost all of which I had never even tried before, and most off which I will buy from Amazon in the future with Subscribe and Save... so it's win/win for me and Amazon.
I also used the $5 off a $10 physical product coupon to purchase another case of one of those items with S&S, though I didn't get the regular S&S discount so I ended up only saving an extra $3.
I've also bought several $1 e-books that I otherwise would not have purchased, including the first of a mystery series that I ended up liking and will probably buy more of those. Clever Amazon making me spend more money! I normally only buy free books or borrow from the library and normally never even look at the mystery genre.
That's about all I've saved so far, but if I had been in the market for a notebook computer or HDTV I could have saved a lot on the purchase... those were some very nice discounts on a large selection of high ticket items.
I'm pretty careful about not buying something just to get a discount, but if it's something I was already considering the extra discount might push me over the edge to buy from Amazon. Only if it's a significant discount though... I'm pretty frugal.