I know of a handful of ethical spellcasters who offer their services on eBay. Most of the lot is comprised of frauds. Same goes with the internet. Some of the best, most powerful magical minds around these days offer their services to people over the internet, but it's very hard for someone without experience to be able to tell who's a fraud.
I wrote a guide for eBay on exactly that point offering tips for people looking to hire a good worker:
another link that's not so crazy: