I recently replaced my 4900 (with a P5000) and I have a brand new, unopened LLK cartridge (T6539) for the 4900 that I can't use. Expiry date is 2020/09/26. I am in Canada, but I will mail it to any North American address, if you pay the postage. PM me if you're interested.
UPDATE: An adopter has been in touch; cartridge will be on it's way soon.