Anyone help with the cheapest place to get a catalytic for my 02 bugeye

I would say Ebay or scrap yards, might have one. If it's for an MOT always worth having a word with some people, you might get lucky or have a friend of a friend that knows someone who knows someone. that will be happy to errrrm forget to use your car and use one that will pass the test if you know what I mean ;)

yeh i'd go round different testers to see if they will pass it without if tht's the issue, or borrow one from someone for the mot