Lexus is 250 amplifier

My Lexus amplifier has been broken for quite a while and a brand new one cost quite a bit, is there a workaround to this that doesn’t involve buying a cheap speaker or use my phone as a speaker?

I know I’m asking a very wide open question but if anyone has any ideas please let me know.

A friend mechanic said I could also buy an amplifier from another car brand and could also work, I’m not 100% sure that works