It's true that there's little or no competition that is like ebay. That's what makes their high fees worth it. If they're not singular, they are close to it. Their service is worth what they get or what you pay for it.

But there are alternatives. You can sell by newspaper, word of mouth, craigslist, other classified ads, OR you could choose not to sell it at all. That is a choice, and it completely avoids the fees.

You can also give your stuff away. That's how I get a lot of my bikes. People with no time, such as when they're moving house or just cleaning up, just want the bikes out of the way. And because people send so much good will this way, I give a lot of them away.