How can I promote my low-cost custom t-shirt business to local customers?

I sell 100 custom print t-shirts for $500 to people in Toronto.

It's a good side hustle, while I work on a startup.

If you guys had a local t-shirt printing business, with prices cheaper than almost every competitor, what are some unique (and cheap) ways you'd promote it? Who would you promote it to?

My goal is to get 5-7 sales per month.

Any tips?