I havent had one of these apart, but I just went and looked at the one on my 502.
I'm sure thats just your typical Torrington bearing, as used in the transmission.
My pulley is all assembled, so I cant see a number on the bearing, but it looks to me that it's just a pair of B1212's. (.750 ID, 1.000 OD, .750 long). These are $6.12 each at Motion Industries
https://www.motionindustries.comThe circlip would be generically available too.