I'd check with the International Students office at your university.
It's my belief that a student visa does not allow you to work while you are here, even if you are self-employed.
You are supposed to arrive with enough resources /money to support yourself and not to "take a job" from an immigrant, permanent resident, or citizen.
Ah.
You are allowed to work limited hours.
https://www.canada.ca/en/immigration-refugees-citizenship/services/study-canada/work/work-off-campus...
Before you list anything set up a Managed Payments account so you can get paid.
EBay needs two forms of government issued identification and a chequing account with a Canadian bank.
Depending on your home country a Payoneer account may be more useful -- or you can register in your home country and list on dotCA, dot COM, or any site around the world.