1045 or any medium carbon steel would be fine. Problem is these can be difficult to machine on a small lathe, at least to get a good finish. Your best approach would be to turn the bearing sizes about 0.001" to 0.002" oversize and then carefully finish them to size with a fine file and emery cloth. It will take several miuntes and you need to creep up on the final size gradually because you need a tolerance of 0.0005" or so.
Take care not to get hung up on a spinning chuck with either the file, the emery or the sleeve of your shirt and only run at 200 or 300 rpm for the filing and polishing.
An open mind is a virtue...so long as all the common sense has not leaked out.