Given that CeX are currently selling a B grade 8GB iPhone 5C for £140, the Ideal World price of £159.99+£4.99 P&P is actually fair value for what you get, though beware that 8GB storage isn't exactly big by any standards: https://uk.webuy.com/search/index.php?stext=iPhone+5c§ion=
So how did Ideal World manage to get hold of brand new iPhone 5C stock? My guess is that Apple are now getting rid of the spare phones they had kept aside for contract/warranty replacements, especially as they come with an Apple warranty. Now if it had been the 16GB version I might have been tempted...