No need for $180 ones for either touring or grocery shopping. I got Nashbar's Waterproof rear panniers when they were on sale for $30/pr. The initial use was for touring but they've been my standard way of hauling groceries home as well. Also got some generic rear rack for less than $10 around the same time. It holds my weight without any problem, so 60 or 70 lbs. of groceries are not an issue at all (my usual load is less, but it gets that high when buying lots of liquids and other high-density items). The rack and panniers have been in regular use for over 5 years now and still seem as good as new.