What do you use as self defense?

I'm 5'1ft 129lbs and I usually carry a pepper gel. I'm usually out on the bus or walking by myself or with my mom's small anxious dog(gives me anxiety). Only thing is I keep it in my purse or backpack. But it's still sometimes hard to reach. I want to take self defense classes. But I can't afford it. Nothing has happened. But a few years ago I went to school in the Bay area in California. I was on my way to visit home waiting for the bus. A lady asked "hey you wanna get kidnapped?" she was with a guy... Nothing happened. it was over a year ago. But still. I grew up with 6 older brothers but they all have Their own families now. If you took self defense classes how much Did it cost? The world is crazy. Also it's a good way to get frustration out.