K03-015 is the KKK part code for the turbo. The 015 is the variant of the k03 turbo as there's a different ones fitted to different engines with different inlet and outlet arrangements. You just need one from a b5 passat 1.8t or an audi a4 of similar age with 1.8t.
If you don't want a chinese copy then you're looking at 2nd hand. Either ebay as Rocket has done there or scrapyards. They can be had for £50, both the ones I've got were £50.