Try these. Big, cheap, durable and simple. http://www.mec.ca/product/5024-315/m...ling-panniers/

The very reason I carry reusable grocery bags. Leave the Panniers attached, and take the bags inside. Come outside, drop 'em in the panniers and go.

My advice is always this: Don't buy panniers that attach using just hooks and a bungee. These have an unfortunate tendency to fly off when you hit bumps, and/or shift around on the rack.

Either get ones that have hooks that latch on (Ortlieb, Arkel, and some others) or ones that have conventional hooks but a much stronger connection to the lower hook on the rack. I use Inertia Designs panniers, which have the latter system, and they have never fallen off. They have also been extremely durable over many thousands of miles. This is what I have: http://www.amazon.com/Inertia-Design.../dp/B001OS43DM

A couple people suggested the Nashbar waterproof panniers. I had a pair of the large size, and they basically fell apart under similar usage to my Inertia Designs panniers, which have held up great.

This is one of those times when it makes sense to just spend the money up front.

I'm gonna recommend a set of Axiom LaSalles. I have 4. Just use one for commuting. Other 3 in rotation or camping trips.

It features a main compartment with a drawstring, really simple but effect hook mechanism and a strap so I can throw it over my shoulder and pretend I'm a bike messenger.

love my ortlieb office, hate my ortlieb downtown.

holla if anyone wants to buy/trade.

I bought these bags about two months ago at an LBS after my pannier bit the dirt. I have been very happy with them so far, and even brought home a 12 pack and some groceries tonight with them. My only wish is that they had a shoulder strap. Often when I'm making several stops shopping, I don't like leaving my pack and goods on the bike. It would be nice to throw the whole thing over my shoulder to carry into the store with me. And for trips where I need more than a 12 pack, I zip tie a milk crate on top of the rack and I've got a spot for the bulky groceries and the smaller items go in the bags. I also use them for work, the change of clothes go in one side and lunch and coffee thermos in the other. But again, they just aren't well suited ergonomically for carrying off the bike.

Or how about bike buckets.. ?