If you are a subscriber to the Arca Swiss stsytem, in other words the tripod plate system with jaws that clamp like Jaws, then you appreciate just know how expensive the accessory plates can be. I recently bought a few 'similars' to the big names, like Kirk and Really Right Stuff, courtesy of FotoPanda on Ebay. Although I was sceptical at first, the quality is good, so I thought I would spread the word. You could say 'a plate is a plate' I guess, but these do the job really well and I recommend them.
The way to access them is thorough Camera Gear UK - http://stores.ebay.co.uk/cameragearuk/ - Their delivery is swift, so I can recommend them