Waldorf, the link you provided is for going from Component to a PC's DB15 connector.
I think the OP wants to go from 3 separate BNC RGB cables (and Sync) to 3 separate Component RCA jacks.
The company you linked doesn't seem to offer such a converter that I could find. The OP has more of a commercial device and I would think $120 would be a good price if such a device could be found, I haven't seen one but that doesn't mean it's not available.
OP might want to check
Monoprice. Here's a copy/past from the Knowledge base tab on this product.
Question: My display has composite (ie: combined) sync with only 4 BNC inputs not 5. (Examples: Barco 7xx/Cine7 or Ampro). What cable do I order? How do I hook it up?
Answer: Order the GREEN (5-BNC breakout cable) and combine the H/V sync lines using a $2 BNC T-connector like this. You could also use an Extron 109 or 202 box as well to combine the two sync lines.
The confusion seems to be when someone searches for RGB they generally get the DB15 PC variety and not the three separate cables as used years ago or commercially. I searched for BNC at Monoprice and got the above device (which I'm not sure will do you any good). It seems to go from 3 separate RGB to the DB15 which you'd then have to convert to component.
Monoprice searching for BNC.