G'day kymcop125, this is not much help to you but, I don't think they used shell bearings on these engines, I believe they are roller bearings. You can get them rebuilt, but it is a specialist job, certainly not something I would try at home. I don't know about the 125 engines, but for the smaller 50cc engines you can find crankshafts from various aftermarket companies, I bought mine from an ebay seller who goes by the name autotech355, also uses Dr.pulley886 as another user name.
Have a look around, if you can find one it will be a lot cheaper than genuine.