I'm sorry to hear about what happened. I'm pretty sure that there's a law against sending harassing emails. What this buyer is doing is wrong and there should be somewhere you can report this to aside from eBay.
If you have a look at the posts here, you will find that there are quite a lot of people who feel the same way as you do about eBay. Refusing to provide assistance to members, much more a Powerseller, is downright wrong. If you call eBay again, you might want the call to be escalated to a Resolutions Officer or a Manager who CAN do something about the situation. There should be someone who can do that within the company.
Here's a link to a list of PayPal/eBay phone numbers, direct lines and email addresses that might help:Link hidden: Login to view
To answer your question, there are a lot of other auction sites that you can sell on aside from eBay. You have Amazon, eBid, Bonanzle, Atomic Mall to name a few.
Here are links to related posts: Link hidden: Login to viewLink hidden: Login to viewLink hidden: Login to view
If you check out these posts, you will find eBay alternatives that our members recommend. You will find some reviews and feedbacks which would help you decide which auction site is for you.
Have you thought of getting your own website? eCrater.com, Zencart.com and Auctivacommerce.com offer easy and cheap ways to get your site up!
I hope that this issue will be resolved soon.