looking for a carb for a 2000 artic cat 500 4x4 green will any other carb except the OEM which is about $500. work on this unit

 

There are Chinese knock offs, but they seem to be hit or miss. Exactly what is worn out? Should be able to rebuild, it's a Keihen, well made Japanese carb, they also respond well to a "Dynojet Kit". Unless bad gas has eaten it up, usually can get them back and working. Also, as I remember the older ones were less fussy with the choke. I suspect one from a 2001, maybe a 2002 might work. I had a 2001 500 and a 2002 400, other than jetting, they were quite similar. Try eBay, never know.