The wife used to do a lot of food "couponing" getting coupons off eBay. For $2 she'd get a envelop full of coupons for stuff we wanted. And that's the real trick with coupons --> don't buy a bunch of stuff you wouldn't ordinarily get just cuz you got a coupon. We shop at Bi-Lo where they have a lot of buy-one-get-one-free items, and they also double coupons up to 55 cents. It wasn't unusual to get a basket of items nearly free. Since then, I think eBay raised prices on sellers and made couponing not as viable. Wife doesn't do it anymore, but you might want to check it out.
As far as retail shopping, a lot of places price match with other retailers and Amazon. Heck, some of the stores have online sales that are not displayed in the store. Just a few weeks ago I price matched BestBuy with BestBuy online. iPhone has really worked out great being able to check prices in the store before buying. Also, if you have looked up an item on their web site and the price goes lower they'll often send an advertising e-mail. You can take in your receipt and get price matched. Between price matching at Amazon and then later with BestBuy's lower price after the purchase, I ended up getting an advertised $200 printer for $75. I've done the same with several items.
Also, keep an eye on the ad banner on this Forum. I had been surfing the Net for a Surefire P3X. A bit later an ad from B&H Photo displayed on the ad banner here for $150. Bought it. Never seen it priced that low again.