I don't see a difference by category, I see a difference by type of item. I am typically selling several thrift store/garage sale finds every week (not bicycle stuff). Some stuff has a a strong following, some has a very limited audience. On the limited audience stuff, I tend to start the auction at a high price, and often I just get one bid. On the popular stuff, I start them cheap, usually 99 cents.

I don't bash ebay, as it is one of the only ways I can get market value out of obscure items, like the Kelty Base Camp kid carrier/backpack I sold last week. No way could I have sold it locally for more than about $10.

Some people expect an online auction to work just like an in person auction. They just don't work that way. Sniping is the only way to go if you want to increase your odds of successfully winning an item without exceeding your target price.