If you can't afford a vet, for mites, you could get Revolution for cats. Its over the counter. But you have to get the dosage right. Here's a link online about it. (don't use frontline because it will kill rabbits very toxic)
[ame]https://www.youtube.com/watch?v=YyqNwCCRSq8[/ame]
The other thing it could be is ringworm which is a fungus. For ringworm you need a fungicide and people have said they use athletes foot creme, but if you do that make sure you do your own research and look it up and see if its toxic.
One good thing about going to the vet, is hopefully they would be able to look at a skin scraping under the microscope and see what it is.
You could also use google "rabbit ringworm" and "rabbit mites" and look at the google images to try and figure out which one it is.