|There are lots of sellers still out there. As was pointed out Dot Matrix is alive and well.|
If you can't find a replacement cartridge you should be able to get yours refitted with new ribbon. Contact some of the companies found by Googling. Link below.
BTW, I never heard of that brand. Good chance it is a rebrand from a major manufacturer. Again, help is out there. I wouldn't recommend trying to re-ink the ribbon. The cloth itself gets broken down and the results will be less than desirable.