4 or 5 would be a good start slowly building them all up together.
It will take a few months to be able to sell 100 items per month across them mind you
I would go with 4-5 just like James said, the problem with just 1 account is that it could get limited and you have to buy another one. Spread your risk across accounts. It may take a little longer but it will be worth it.
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