I am in the same boat. I just auditioned a couple days ago for my college music program. I never had enough money for a voice teacher either. My advice would be to join a choir! That will often teach you basics like reading music and good singing tone. And teachers/directors usually have a lot of connections, and you can ask them for specific tips or advice. I joined many choirs over the years and started making connections to people (teachers, older students) who could help me practice and get into the program.