Well, not strictly true as selling on eBay is no fun at all. However…
It really is quite simple to make an extra £50 to £100 a week by buying at Boot Sales and selling on eBay. A Boot Sale, for those who don't know is basically a gathering of people who sell stuff they no longer want at (usually) rock bottom prices. http://en.wikipedia.org/wiki/Car_boot_sale
The things to look out for are items that you can double your money on and easily post.
A good example is computer games for the Wii, Playstation and so on. It is easy to pick these up for anywhere between £1 and £10, and can be resold on eBay for anywhere between £5 and £30! Easy to post as they slip into an A4 envelope and cost only £1.49 to post anywhere else in the UK.
Other things that can make good money are designer brands such as Faith, Ugg, Dr Martens, Nine West and so on. Usually I pay between £2 and £5 for shoes and can easily resell for as much as £35. Good sellers are those shoes which have no wear or almost no wear (and a box does help the end price!). Most important thing is the amount of wear, less is better.
Old collectables and toys also sell very well on eBay; Pelham Puppets, Matchbox and Dinky Cars, Corgi – ALWAYS ensure that you buy the items inside their boxes. No boxes, unless it is something in very good codndition and relatively rare, should be avoided. Star Wars stuff always sells well on eBay, with original figures trading at anywhere between £1 and £300!!
How about modern things? Match Attax (football trading cards) sell well IF they are "limited edition". If you come across someone selling Match Attax, go through them to see if there are any "limited" ones. They all say "limited edition" on the side… These can go for anywhere between £2 and £250! It's not just Match Attax- Super Strikes is another. Again, look for "limited edition".
Camping Equipment – Trangia, Kelly Kettle, lightweight sleeping bags. lightweight tents. All this stuff sells very well on eBay. Also hobbyists tend to look for things; model railway stuff (ensure it is boxed)…
What I usually do is visit a couple of boot sales, with about £100 in my pocket. I sometimes spend it all, I sometimes spend nothing. Whenever I do purchase anything for reselling, I try to double my money at least. So if I buy something for £5 at a Boot Sale, I put my starting price as £10 on eBay. That way I ensure I'm into profit (after all the eBay fees and Paypal fees).
A good tip; have a wander around a Boot Sale with your smartphone on the eBay search page. If you check "completed listings" you can find the typical prices that things are going for, and this will give you a guide price of what you should be paying the seller (remember that half price is the maximum you should pay).
Once you've sold your items on eBay, then comes the boring part of packing it up and taking to the post office. But, hey ho, you will have made a bit of profit.
Another good tip; don't be scared to buy something and split it up. you don't have to buy the things you sell, you can easily sell part of them. If someone needs something to complete their own collection, they may pay as much (or more!) as you paid in total at the boot sale.