There's a lot of PayPal coupon codes floating around (for example CANDY gets you £5 off a single £20 before postage ebay.co.uk auction before 21/09/06, search for others). They're usually only valid for the people they were personally sent to, but you can test if it will work on your account without buying anything. If it DOES work even though you weren't sent anything to say it would, please post to give people more incentive to check!
1. Either search eBay.co.uk for anything like you normally would (type something like "computers" in the search box) or browse a subcategory (from the front page click on something like Computing and then Desktop PCs). Then put this in your search options (on the left of the page), changing 20 to the minimum price for the coupon you're testing:http://img157.imageshack.us/img157/6374/searchrm3.png
2. Find an item out of those that says immediate payment is required (if it doesn't say this then you'll commit to buying it when you push buy it now!). Doesn't matter if it's quite expensive since you're not really buying it:http://img96.imageshack.us/img96/2569/immediatevm5.png
3. Click buy it now and keep going through to the paypal checkout. Don't really buy it! There's a space on the paypal checkout page to redeem a coupon. Enter this coupon and click redeem.http://img96.imageshack.us/img96/978/redeemld9.png
4. It probably won't work for you if ebay or paypal didn't send you the coupon personally. So you'll see this:http://img157.imageshack.us/img157/6261/nonl4.png
5. Before backing out of the paypal checkout, you could try some other coupons if you think they might be valid on this auction. But they probably won't work for you unless you've been sent them personally, and even then you might struggle to use them (there are hidden rules and paypal support is terrible).
So, you've found a coupon that works for you. What do you want to buy? Using the search tricks above you can find something like UK items with paypal, costing £20 to £25, ending soon. Remember to read the rules for that coupon and that the minimum auction value doesn't include things like postage. Still don't want to buy anything?
For one coupon, I created an eBay buy it now listing for cash (there's a banknotes category!) on a family member's ebay/personal paypal accounts. That doesn't break any rules that I could see (and paypal support were aware of the auction and didn't complain about it or report it) as long as it's a buy it now format rather than an auction format (if it were an auction, friends or family couldn't bid because it would be shill bidding).
If you agree that it doesn't break any rules and you're not buying anything off ebay but you're entitled to use a coupon, then try this. Even better if you can do it on a 5p listing day! I had to pay but £1.50 listing fee for a £50 auction, but we paid £40 from one paypal account to get £50 in another paypal account. If the paying paypal accoun (the one using the coupon) has a bank account linked to it or an existing balance, then the receiving one can be a personal account and not have to pay any paypal fees.
As I say, I don't think this breaks any rules and PayPal support saw the auction and didn't complain. If you see an eBay or PayPal rule it breaks please say so!