I buy and sell on ebay fairly regularly, including camera equipment, so I'll throw in my 2 cents.
1. Only use paypal.
2. Only ship after you have received the money
3. I'm not saying not to ship to other countries, but I don't. I looked in your profile and noticed you live in NY, same as me. Lots of people from Canada like to bid on these auctions and 99% are clueless about customs and duties for shipping an item from the US to Canada. I have had sales fall through because people won't pay the duty, and I've had to refuse to ship an item because they want me to lie on a customs form. If you declare an item under $20 and a gift there are no duties on it, but technically it is a crime.
4. Make sure to put a CYA paragraph at the end of every auction. Mine goes something along the lines of, "Thank you for looking at my auction, if you have any questions please ask them before bidding. Payment is expected within 3 days of the auction ending. If payment is not received the item will be relisted and an unpaying bidders complaint will be filed. The item will be shipping within 24 business hours of payment being received. Insurance is optional but highly recommended."
5. Don't be too verbose on your description paragraph. If it takes longer then 10-15 seconds to scan if it too long. I will usually give a quick sentence or two about what I am selling then put everything else in bullet format.
6. If there is anything wrong with the camera, make a note of it. Even a minor scratch or rub.
7. Factor in ebay and paypal fees. By then end it will usually consume about 10% of the final price of the camera. There is a fee to list an auction, a fee to end an auction and two fees to use paypal.
8. Always have your auction end during prime time. I prefer between 8-9pm EST because that isn't too early elsewhere in the US. I've gotten some good deals on ebay auctions ending at 4am Tuesday morning. It only cost 10 cents to make an auction whenever and have it start at a specific time. The timer runs off of pacific time though FYI.
9. Consider craigslist as well. With that you get cash in hand (only deal locally and in a public place, I meet inside the food court at the local mall), no fees and if you only leave a phone number to call instead of an e-mail address you eliminate almost every common scam.
Hope it helps.
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Yawn...