I didn't come across this seat when I was looking at booster seats for my daughter, but I wish I had. Each SweetSeat is handmade and the perfect height so those little legs won't get squashed. It also meets my #1 criteria: easy to clean.
The seats are made of laminated cotton and are also portable. It seems to me they could also be used on the floor as well as on a chair. While the price tag of $84 is a bit steep, there is an outlet on their website
where they sell slightly imperfect seats.
See the current collection of SweetSeat's here