Need help with these or similar kind of motors!

Hi I am a beginner in the college's (new) robotics committee and I need help with the motors the following specification.

These were recommended by a winning team at a local tournament. But they say the only way to buy these is through them.

It is for a line follower bot

I want coreless geared motors as

Size: 1220, GearBox- 1:10 ratio, and 2500rpm at 6v

Please any source or help or advice is appreciated