Recently, I've had a couple of people ask me about reselling books, so I thought I'd have a go at writing down the things that work for me - with the hope that some of it may be of use to someone else.
I started reselling books on Amazon.co.uk sometime in early 2002. P had very cleverly spotted that Amazon were starting up a facility for people to sell their second-hand books through the website and it immediately appealed to me - primarily at the time as a way of getting rid of some of the books I no longer needed. For a while I only sold books I had previously owned myself but one day, whilst browsing in a charity shop, I had a 'eureka' moment and wondered what it would be like to resell books that I bought specifically for that purpose.
In those heady early days, it was quite easy to make decent money reselling books via Amazon and at one time I was regularly making £50 per week from this. Sadly, in the last couple of years those earnings have dropped dramatically - possibly because of the recession, but more likely because there are A LOT more people who are selling second-hand books on Amazon now and, naturally, the prices have dropped accordingly.
It's pretty hard to give a definitive answer as to what will be a good book to resell and what won't. I would definitely say keep well away from any blockbuster-type paperbacks, or chick lit or anything that was featured on Richard and Judy's book club. In theory, non-fiction books should be a much better bet and the more esoteric, or downright odd, subject matter the better. Some of the books I've got listed on Amazon cover unusual subjects like Killer Whales in Twofold Bay, Islands of Europe, Lullingstone Roman Villa and Mathematical Programming in Practice - not easy bedtime reading that's for sure.
Childrens' books can also be quite good resellers - although, again, nothing that is too mainstream. Look out for books that date from the 60s and 70s, there is often a good market in nostalgia for these books. Condition is fairly important with them though as no-one really wants to buy a book that is covered in scribbles or has a previous owner's name scrawled all over the cover.
If I spot a likely looking tome in a local charity shop - but it costs more than 50p (and most books do these days) - I'll jot down the ISBN number and check it out at home to see if it would be worth buying. Nine times out of 10 the answer is an emphatic no. Obviously, this is not possible at a car boot sale or at a charity shop further away from home. In those cases if the cost is cheap enough I'll take a chance and buy the book anyway - sometimes this tactic works out, sometimes not.
Any books that are no good on Amazon, I'll check on eBay - sometimes what sells for £2.00 or £3.00 on Amazon can make a tenner or so on eBay. If eBay fails too, I'll try Greenmetropolis. You get £3.00 per book sold on Greenmetropolis although from that you have to take out second-class postage - if the book is larger or heavier than normal you can add more postage fees to the original listing. I tend to only list on here if a) the book is really pretty small and b) I've paid very little for it, but it's a useful site to get rid of items that would otherwise end up being donated back to another charity shop and the £3.00's do add up over a matter of weeks.
Any books you do list (on any site) be scrupulously honest about the condition and state all signs of wear, and do flick through all pages to see if any passages are highlighted, there are notes in the margin or other obvious signs of wear and tear (something I have been known to miss in the past). Rub out any previous prices on the book (usually written in pencil on the fly leaf) and if the old price is still visible, clip the top corner of the fly leaf off - but mention this in the listing.
Store books for sale somewhere clean and dry (there is nothing worse than the smell of damp, musty old books.) I've got my Amazon-listed books in a bookcase in the dining room and my Greenmetropolis-listed ones stored in a large cardboard box (also in the dining room.) Although I do wish we didn't have to live quite so cheek by jowl with my reselling stock. And, finally, if you do have any sales, package the book carefully - preferably in a padded envelope - so that it arrives safely.
Goodness, that went on a bit longer than I expected - I hope its useful for anyone interested though.