Bicycles last a long time, and touring bicycle technology  was pretty much optimized by the 1990s . My oldest bike is 35, my youngest is 15. Barring major accidents, they'll outlive me.
Good bike gear lasts a very long time too. I bought one of my favorite tools in the late 60s. Good panniers will survive at least a decade of the worst winter riding.
Which means it's tough to run a business that sells good bicycle gear. There are no viruses to drive upgrade cycles, and after you've sold your first ten thousand bicycle bags there's nobody left to sell to . The only good news is that bicycle use has been growing for the past few years.
Long lasting gear also means I don't shop for things like bike bags very often, and I don't know where to go . Which is why I'm posting this list of places I visited today. It's made up of a mixture of the usual suspects, plus dealers of Ortlieb bike bags  and stores that market on the best bicycle blogs.
I've ordered them roughly by the quality of the web site:
- Harris Cyclery: Because of Sheldon Brown’s old site, great resource for older bikes.
- Universal Cycles: They have a very well done web site and one of the best selections
- Dutch Bike Bits: Strong opinions well put - european
- REI: Their store brand gear is quite good
- Nashbar/Performance (I think these are same ownership)
- Commuting Bicycles and Accessories - Commuter Bike Store
- Hiawatha Cyclery: A MN shop; informed recommendations
- Buy Commuting Gear | Commute by Bike
- Cyclosource: Cyclosource Store
- Boise bike touring and commuting bike shop
- Gregg's Cycles
- Peter White Cycles Home Page
- The Randonnee Shop
- Wallingford Bike Parts
- TheTouringStore.com: Good information source, but I think you have to phone to buy
- Bike Commuter Store - Amazon.com: The evil empire crushes all on price (until everyone else is gone. Then...)
 Electric shifters? Really? That would be dumb on a touring bike. Even disk brakes are a bit excessive (though I do like them on my mountain bike!). Plastic chains and intra-hub planetary gears maybe one day...
 For most riders in cities with decent bicycling infrastructure the touring bike is what you want. My archived 1990s page on bike/commuting made the case and I still think that's right.
 Maybe that number is higher these days. There are a lot more riders in MSP than there used to be.
 An expensive very high quality elite brand. So only serious stores will sell them. I'm considering the Ortlieb Ultimate5 front bag for my old Raleigh International.
 We have some very good local bike shops -- my problem is schedule constraints. Your life may vary. Many of these retailers are also local shops.
Update: Ironically, after listing these resources and reviewing my handlebar bag options, I decided I would need to make the time to visit one of my local bike shops, perhaps doing a special order there. I needed to see the bags.