It boils down to how many times do you plan on touring. If you plan on doing a lot of it then get Ortliebs, if this is a once in a lifetime touring event then lower priced Nashbar or Performance etc are fine. Problem with lower costing ones is their ability to keep water out of your stuff is usually poor, so consider getting either the waterproof model or buy their rain covers, either way just to be safe put items you don't want to get damp in any matter in plastic zip lock bags. I have Ortlieb's and I still put important stuff in plastic bags even though the bags never gotten damp inside.