Okay, I use to be an extreme couponer a few years ago. I would "buy" $1000-$1500 a month of non food products. It was for a church ministry to help out people in the community. It was things that I could get free after rewards, coupons, and rebates. Because of the tax exempt status with the church, I didn't even have to pay sales tax. In some states, like MO, there's no sales tax if your balance is 0.00. I use to get 6 newspapers, and yes I had to pay for those. Plus I had 3-4 computers I could print coupons from. There would be a lot of items I would make money on. For example, Walgreens might have an item that was free after register rewards. A lot of times there would be a MQ coupon making the item free and you would still get the reward. Sometimes it was as much as $10. I would then use the rewards on other deals like diapers and baby items getting those items free. It was a LOT of work but worth it to help people out.
However, since I started working again (and it's just my husband and I) I no longer do extreme couponing. Having said that, there are some things I just can't bring myself to buy. Black Friday is a great time to stock up on things from Walgreens and coupons are not needed. You can google last year's ad, but free items included digestive advantage, Tums, Gelusil, sleep sheets, dream water, cepacol, shampoo, conditioner, maxi pads, restless leg stuff, dry shampoo, toothbrushes, blister, swisse multivitamins, scunci, toothpaste, protein water, opti-free solution, foot cream, and nasal spray.
Some of the items had peelie stickers on them thus I made a profit and used that money to but the coffee on sale. You just need some cash to start with. I usually start with a $50 Walgreens gift card. If a product costs $5 and gives a $5 register reward, you can then use that $5 register reward to buy another $5 item. Just go back and forth between them to avoid spending cash.
As far as other things, I NEVER buy computer paper. It's free after rebate all the time at Staples. So are batteries around Christmas times and numerous other things throughout the year. Back to school sales are a great time to stock up on office supplies. I'm still using free packing and scotch tape from a coup,e of years ago. I know there's a big push to make your own cleaning products, but when I can get Windex for 0.50 and Ajax for 0.20/can, it's kinda hard to mess with. You just have to stock up on sales and I mean stock up. When SOBE came out, and was free, we bought a couple hundred bottles. Tuna at 0.39 a can might mean 50-100 cans. Just check dates!