I have a rear rack on my Schwinn. It was made by Wald and I want to say it cost about $25 shipped. I bought a bag that was supposed to be a fishing tackle box that fits the rack well and glued (with some industrial spray adhesive) some Velcro straps onto the bag. The bag was probably another $20. I also bought an elastic cargo net that works with the rack pretty well.

Inside the bag I keep 2 bottles of water, a small first aid kit, a tube repair kit, a tube, a few tools, a small cable and lock, and a frame mount tire pump. The bag has a purse strap, so I can bring it in with me if I feel the need.

I put the rack on shortly after I bought the bike so I don't really know how much it affects my ride.

J White