I received Sidekicks Foldable Ballet Flats as a gift, and they were a lifesaver at a wedding I just attended! I pulled them out of my purse and changed into them at the end of the evening when I was tired of wearing heels. Immediate relief for my feet! They are so convenient and comfortable that I even changed into them on my flight home. I now leave a pair in my carry-on for work travel!
I should caveat that Sidekicks are NOT intended to be shoe replacements. They are pretty cheap and fairly thin flats (they have to be to fold up into a tiny pouch) that you can wear when you need a break from your real shoes. But there is no support – these are not comfortable enough to walk around in for a long time! They are just temporary.
After doing some research online about other inexpensive foldable flats, I discovered that Sidekicks generally get the best reviews for comfort, but my one complaint is that the sizing only comes in Small, Medium, Large, and XL. So you might have to try two sizes and return one to figure out what fits you best. They claim that this is how the shoe sizes match up but I wouldn’t place a lot of confidence into it, as I was on the border of Small and Medium: