1995 Chevy Prizm I cant find a way to scan my codes

I have a1995 Geo prizim. The engin light is on and I can't seem to find a code reader. The only person that I found that says they can scan it wants $150 I can't afford that. In the morning the car will start then cut off and it will be several times untill it will stay running. It seems to be getting worse each day. Lately it has been cutting off when i'm at a red light or stuck in traffic. Do you have any ideas? Thank you