Google is your friend. You got to search for them as prices vary alot and it depend what your realy after. I found someone selling cheap homemade winch bumpers on ebay. They may not look as pretty as the 600quis ones,but do the job just aswell.
If you're buying from ebay, make sure it doesn't say "Location: China". If it does, it will take half a year to arrive and when it finally does, it will probably come with a few surprises too.
Seconded, he makes good, strong stuff that looks good and is a nice bloke too ..
Well, as nice as anyone else who'll happily use his rear winch (and front at times!) to tow you round North Yorks hills and woods 'cos you've got AT's on ..