So I didnt actually buy that orange omni-wheel . . . my friend asked me to hold on to her robot like 5 years ago, but she quit robotics and forgot I still had her robot . . .
So I scrapped it for parts
Im so evil sometimes . . . just google around for omni-wheels, you will find some . . .
Anyway, Ive also tried ball castors but I dont like them - they have horrible ground clearance. For example, a 1" diameter ball will give you a .35" ground clearance.