Have you used a pricebook to track prices? I did this a couple of years ago and found it to be too time consuming for me for what I got from it. With only a few stores in my area and two of them owned by the same company, it just wasn't a worthshile strategy for me. I do think that it would probably be very interesting now if I had kept up with it because I would actually be able to put my finger on how much things have increased in the last year, six months, two months.
A few tips if you do keep a pricebook:
1. Be sure you note the package size with the price. If you haven't noticed, package sizes (cans, cereal boxes, frozen vegetables, etc.) have changed - gotten smaller - even if the price hasn't changed much. You start to notice this when a recipe calls for a 12 oz. can of something and you can only find a 10.5 oz. can.
2. Categorize your book by grocery store aisles. This makes locating an item easier.
3. The following web article is a wonderful resource for price books: http://stretcher.com/stories/05/05mar14c.cfm
I would be interested in your success stories on price books. I think the idea is good, but I just wasn't willing to put lots of time into it. Maybe I gave up on it too soon.