How to get rid of cat mites with out going to the vet?

This isn't something you can diagnose yourself and try to treat when you have no idea what you're treating. You can guess that she has one problem (mites) when it's actually a bacterial or fungal infection which need a different kind of medication. If let go, it can cause much worse problems in your cat. Call a shelter or Humane Society around you. They'll be the ones to know of places with reduced fees you can go to for vet care on a limited income.