I own a Performance power dowel jointer. It looks very similar to the Mafell and does use the same style of drill bits.
It came from B&Q a few years ago and I think that the tool with 3 pairs of drills was less than £45 maybe a trip to B&Q could be worthwhile.
The tool model number is CLM600DWL
There is a helpline number on the tool 0845 3002577