I wonder if you've ever tried to sell anything on eBay.
It amazes me how similar items can sell for such different prices. Sometimes it just seems to be a question of timing - the right / wrong people find / don't find your item at the right / wrong time.
But I'm pretty convinced a lot of it has to do with the quality of your descriptions. I used to move a bit of stuff on the 'Bay and got pretty decent prices for it - on one occasion selling a secondhand item for considerably more than it was worth new.
I worked with a few simple principles on eBay:
1. Be completely honest. If the item's not rare, don't list it as rare. If it has faults, point them out. Some of my listing titles have included the words 'NOT rare', 'Common as mud', 'More common than mud' - and I got great prices for all those items. Honesty is attractive to buyers. This also applies to postage - don't rip people off.
2. A listing is nothing without good photos. Give each listing at least 4 focused pictures, being sure to present as much detail on the item as you can, especially in areas where buyers are looking for detail. A lightbox, or a backdrop that contextualises the item, might be of assistance. An 'action' shot like the one above is good to include - it opens people's minds to the possibilities of what they could do with the item.
3. Give the item a really thorough description with the best grammar and spelling you can muster. If you can demonstrate a little technical knowledge of the item, that also helps.
4. Tell the story. People are curious, and love to know the history of where the item has been, which celebrity owned it, and which side of the American Civil War it fought on. This is the non-tangible, non-spec side of things - but it makes a difference, and adds to the character and uniqueness of your item. Stories give context to raw data.
5. Start the bidding low. This gets things moving. If you've got the above ingredients right, you'll get a sale and it will probably be at a price you're happy with anyway.
6. Finish items at a time when people are likely to be home. Most of mine finished in the evenings, and the bidding always heated up in the last ten minutes. Evenings were kind to me - not many people would feel comfortable bidding in front of the boss at 11.15am!
What are your eBay tips for success? Can you sharpen up these points?