I am writing down a few thoughts on the subject of buying on eBay. Some are just opinions and some are the result of hard experience!
ALWAYS check postal costs - this may seem obvious but a 'bargain' may not look so exciting when you realise the FULL cost. BEWARE of listings where the price is ridiculously low but the postal costs are excessively high - this is a scam because you can not return the item without being badly out of pocket! i.e. if an item is 0.99GBP & post is 160.00GBP, if you realise that it is rubbish, you will have to pay return post (Perhaps 10.00GBP) and your refund, if you get one, will be 0.99GBP - now you are short of 170.00GBP and no goods! This is a favourite trick of dealers from China - Look particularly at their feedback as well - often 10 to 20 feedbacks ALL ON THE SAME DAY! Yeah, right!
Avoid sellers listing in non UK currency on UK eBay - why would they do that if they are UK based?
READ FEEDBACK. You may be buying from a 'buyer' who has many feedbacks but sells very little. If you're buying, read their selling feedback.
If you are buying, READ THE LISTING! Read ALL the requirements stated by the seller - I have had many bids from people who obviously don't read listings! It is very annoying and time wasting for both parties!
Decide before you bid whether or not the postal charges are reasonable! It is not acceptable to complain, after winning an item, that the post/packing was excessive!
Be wary of bidding against 'hidden' bidders! This can be used to hide SHILL BIDDING which is against eBay rules. Shill bidding is a way of entering bids to raise the price - These bids may be from another of the sellers accounts or from friends but can be withdrawn after bidding has reached a high enough level! If the bidders I.D. is not listed, you should be suspicious!
Watch out for listings where the item location is something like: London, China! Does that sound like an honest dealer?
Decide before you bid what the item is worth to you! Don't get carried away with 'Auction fever' - there will be a similar item along later!
A last piece of advice (bitter experience!). Try not to List items or Buy items on a Friday - This is the day that eBay chuck in a load of, apparently, untested software! You may get all kinds of weird results! I do know something about computer programming - I started in 1974 on PDP8e's!
REMEMBER - there are millions of happy buyers who have discovered a treasure on eBay, so it is a fantastic marketplace - just TAKE CARE to avoid the unscrupulous - the signs are usually there!