I had the same issue a while back. I didn't have enough $$ to buy Arkel or Ortlieb. I bought a basic rack (Delta), and I bought the Detours Toto messenger bag/ pannier ($45). If you have the cheddar to spend on a high-end item, go for it. The Detours bag has worked well for me, though it's not a big bag. It's surprising how few companies make messenger panniers. Timbuk2 also makes one, but the set up on that doesn't look secure to me. Regardless, I am so happy I made the transition to panniers. Haven't looked back since. Good luck.

http://www.llbean.com/llb/shop/60105...-toto-bike-bag