you can get them from any decent bearings shop. 10mm by 9mm thick take the measuremens of the interal diameter , external diameter, and width. they are the same as mini moto berings too.
problem is, at 9 quid a pair, plus if your bearings are knackerd, your spindles may well be corroded, and they need to be a nice flush fit, otherwise they wobble, is it cheaper to buy a new set of zytecs...