Em, if your cat needs antibiotics or steroids, get them. I'm also a bit of a hippy (vegetarian etc) but have to take regular meds which I know have been tested on animals, I have no choice if I want any quality of life. I've got neutropenia (immune deficiency) as a side-effect, so even the most minor infection means more antibiotics, cos I can't fight them. So sometimes you have to compromise your principles and choose the lesser of evils, in your case, choose your cat's health.
If money is a major issue, do you have someone who could give you a loan? A partner, work colleague, family? It may be a good idea to get insurance for the mog.
Generally, I agree with Lynn about your course of action: to the vet, antibiotics, steroids and tests.
Until you go to the vet maybe stop picking the scabs off, you're leaving exposed areas. When the scabs are healed they will naturally fall off. Maybe bathe the area with a saline solution (boiled water allowed to cool, put half a teaspoon of salt into a mug, fill it with warm water, allow the salt to melt) and cotton wool. Don't pick off the scabs. If your cat really dislikes this, you've used too much salt. This will act as a mild antiseptic and healing agent, but is no substitute for FL spray and the above mentioned things from vet.
Your cat is in discomfort, take action.