Factory shops - near us there are a couple of good lighting factory shops that sell lights much more cheaply than they sell them in the shops. Although they say they are seconds, it's often very difficult to see the flaw, especially when you think that with lights in particular, they will be up on the ceiling and especially when switched on it's difficult to look at lights much as they tend to dazzle so people won't be able to stare to see teeny weeny imperfections!
But it's worth investigating if there are factory shops for things like handles or other bits and bobs that you want, they are often a great place to get good bargains.
We also used to live near a Dwell factory shop - which sold returns and bits that weren't quite perfect. We managed to get a table and bench for about 15% of the perfect price - so a massive saving. There's a scratch on the table but I have young kids and figured that the table wasn't going to stay pristine for too long, plus I always have a cloth on it to protect it, so it's never seen so for several hundred pounds worth of saving it really didn't matter! The shop is no longer here, but I don't know if they have other factory shops elsewhere.
Motto is though - if there's a brand that you like - it's worth ringing them up to find out if they have a factory shop or somewhere they sell returns so you could check it out to get things you love much cheaper.
There are also places that sell second hand show kitchens - either from kitchen showrooms or from show houses. Sometimes kitchen retailers will sell them off cheaply themselves. Again, worth investigating.
People sometimes sell their old kitchens on ebay - or fittings or doors - so it's worth having a look, just on the off chance you see something you like. Also consider putting your old on on there - you never know, might be just what someone is looking for and even if it's not for much, it's more than you'd get throwing it in a tip!