I got a pair of Sport-Packer Plus panniers from Sierra Trading Post for just over $100, which are now my daily commuting bags (well, I usually use just one). You have to keep an eye on them and get lucky, but they often have bike stuff you wouldn't expect. I've gotten bike gloves, jerseys, shoes, etc. from them too. Pro tip: sign up for their email and wait for a 20% or 25% off coupon. They come frequently.

https://www.sierratradingpost.com/s~ortlieb/

And Ortlieb customer service is indeed excellent. I managed to break the bar on the back that holds the attachments, and had a few other issues with broken clips, a broken strap, etc. I called customer service, and they sent me replacements parts for everything that needed it, no questions asked.