Ortliebs are indeed expensive, are they the best though? that's arguable. But due to the price I skipped those and went with Axiom Monsoon Hydracore 45's but I also got them on sale for $119 for the pair. The Monsoon's are designed like a dry bag, and they successfully kept the inside of the bag dry during a 4 hour ride in a downpour coming home once from a mini tour, and that was without the optional rain cover! Even my Topeak Tourguide DX with the rain cover on got damp inside, so the Monsoon's work very well at keeping water out. The retaining system also works very well, but I like to make sure the bags stay firmly on so I used short small bungee cords with the hooks, which I had to use anyways to secure my tent ( also in a trash bag) to the top of the rack, so while I'm securing my top load I simply reinforce the panniers so they don't bounce around. I have nothing negative to say about those bags after using them a lot this past summer. Now if you are only doing a bike tour one time a cheaper pannier will work just fine, and to add water proof protection just do as I'll explain below.
As a side note I do use a 30 gallon plastic trash bag inside the Monsoon's as a liner, it serves a dual role, the most important role for me is that the trash bag keeps anything that might leak from staining and gunking up the inside of the bag; it also serves as another water barrier but in that storm I went through it would have done nothing in that regard because nothing got wet or even remotely damp. Because I am paranoid about things getting wet or stuff leaking outward, I put all my stuff in ziplock bags.
Rack wise I also use the Tubus rack, not sure if there is one that is equal to that rack. The issue with racks is aluminum racks are known to break at the welds depending on the weight being carried and the amount of jarring the rack is enduring. Also AL racks are not as stiff as steel and a steel rack can actually stiffen up the back and forth (swaying) motion that the rear triangle can go through when riding with a load on the rear and going fast like down a hill. So since my bike was built in 85 and the rear triangle on older touring bikes were known to sway which it did when I tried using the stock AL rack, though it wasn't violent swaying but I decided to go with the steel and never noticed any swaying after that. The original AL rack was a Blackburn model contracted by Schwinn.
When doing backpacking or bike camping there are certain items you don't want to go cheap on, the most critical are your bags, followed by your tent. While you can find a very good tent for around $100 or so like the Alps Mountaineering Mystique 1.5 (person tent, the extra 1/2 gives you room to store your panniers inside) tent works very well in all sorts of weather. I also didn't go cheap on my sleeping pad because I have a back problem so I got the Therm-a-Rest Neo Camper which is thicker but heavier but it was worth as I found out sleeping on it and not having pain in the morning. But other stuff like sleeping bag and camping cooking gear can be found rather cheap and work fine, in fact I got a lot of my stuff from Walmart including my sleeping bag! Food you don't have to buy expensive (and salty) camping food, there is all sorts of stuff in the regular isles of the grocery store that are in foil packages for microwaving that you can cook easily on a camping stove and cost far less per meal. You would be surprised at what food you can get that while in neat foil packaging that does cost more then stuff you have to put in a frige to keep but the stuff is still cheaper than camping food. Camping food can cost $7 to $9 per meal, the foil stuff and some Top Ramen a meal might cost you $3 to $4; I take eggs, and in America they wash the skin off which shortens the life of the egg if left unfrigerated but they're fine for up to 3 days, 2 days if above 80 degrees F.
View: https://www.youtube.com/watch?v=Uu1CMjmSY9I
View: https://www.youtube.com/watch?v=5wT8OZVTEWk
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