This easy on, easy off pannier is super cheap and works fairly well.  I’ve been stuffing my man purse & grocery shopping stuff into it for a long while now and its holding up really well for the price.  Folds in and out of the way easily with velcro, even comes with a rain cover that actually works.  Reflective strips all around.  No, you dont feel off balance riding with only one pannier.  I hate to sound like a pimp but its on sale now for 9.99! I think today only at Nashbarf.

Good for holding camping stuff too:

 

 

Here it is on a rainy ride.