Which Coupon Clipping Service Do You Use?

So I have a question for my readers & lurkers. :)

I am in need of quite a few insert coupons. I would rather not buy off of ebay.com, which leaves me with trading or buying. I am searching to buy my coupons from an online coupon clipping service. But which one should I try?

I have purchased coupons online before, but I'm trying to find one site thats has all of the coupons I am looking to buy. And of course, I'm trying to find the best deals for these coupons. I don't mind purchasing from multiple sites, but I would like to find at most two (maybe three, but that's pushing it) sites to buy coupons from.

So, which online coupon clipping service do you use?

Or which sites have you heard of, or would like to suggest?

Please help, I need to place my orders as soon as possible; and would love to hear from my readers ( & lurkers)!