It's a nice shop for getting some inexpensive robot kits like some arduino stuff.Maybe the customer service there isn't that good at robots,but the products they sell are great.
Kornylak Corporation offers a one stop shop for all of your Omniwheel needs. Let us know if you can't find what you're looking for in our online store!
For more information about Kornylak Corporation and our multidirectional wheels for robot applications, please visit: http://www.kornylak.com/robots/robots.html
yourduino.com is cheap and honest, but they have a somewhat limited repertory of products