Thats correct suits cost a lot more than that, and the loser usually pays it all; so watch yourself. Plenty of domain disputes and & cybersquatting type cases on the books for you to review.
A coulple organizations to check out for research.
IMO it appears you clearly knew about playunited when you purchased those domains. You also seem to have had an intended usage or intent in mind.
Sorry, but I wish they would just stop the talk and sue you.