In searching for online printable coupons, I came across people selling coupons on Ebay. While they technically don't sell the coupons themselves (doing so would be illegal), you are paying for their time and handling.
So, I gave it a try, twice so far.
My experience has been good and the shipping seems to be pretty quick. I have only searched for multiples of specific coupons that I was wanting, but I do see where you can buy a lot of say 100 grocery coupons. I don't think I will go that route, because there are just so many coupons out there. I would rather know exactly what I'm paying for and getting.
For example, I ordered a total of 20 coupons for items that are on sale this week. If you check your ads as soon as they come out and order the coupons right away, you will most likely get them before the sale is over. For the 20 coupons, I paid $2.00. Shipping was free. If I use all of them, which I'm planning to do, I will save $17.50. So my net savings will be $15.50, minus the less than 5 minutes of my time it took me to find and buy them on Ebay.
I know some stores have a limit on how many of one specific coupon they will take, so you might want to check on that before buying a lot of multiples.