I don't sew very well so my only option is hard sided panniers. The various crate-based and cat litter box-based panniers I have seen on Instructables look like they would work well but none of them had the look that I was searching for. I also felt that changing the configuration of the hooks could make them alot sturdier and less prone to fatigue.
Kingsford charcoal began making these waterproof containers a few years ago to hold and dispense their charcoal. When I saw these boxes at a hardware store last summer, I thought they would make a great pannier because they wouldn't stick out and they are made of very sturdy and resilient plastic. So I picked up a pair for about 20 bucks (all said and done this project was under $30)
I made a bracket out of some oak scraps that sits on top of my bike rack and holds the two poles that the boxes hook on to. The poles are from an old tent that are cut to a length that allows a rope strung through them to keep the panniers from sliding off. A pair of bungees keep the boxes from bouncing out. Eventually I will make a more elegant solution like the Arkel and Ortlieb hooks that latch but for now this works.
The hooks are 3/16"x1" flat steel bar that is formed into a hook with a vice and a big hammer. They are epoxied and bolted on.
So far I have ridden about 200 miles with weights between 30 and 65lbs and I have had no problems at all. Proper loading is important for panniers so keep the heaviest loads low and they will work great for you. This summer I'll be training for a 200 mile 3-day weekend camping trip and these panniers will be a big part of it.
I hope this Instructable is helpful and not too much of the same old stuff. Cheers!