R M Equipment has been around and making their version of the 203 for a while now, at least since the 90's. I'm not familiar with their pricing. They advertised their version as fitting many foreign weapon systems, but I don't know if they have one standardized receiver, or multiple models.
All the holes in that pic would suggest a standardized receiver.
The downside is lower height (on AR family), and it's probably a few ounces heavier.
That price looks tempting though.
I'd call RM and get more details about their design and mount availability. Also ask if they've sold factory seconds, anything with problems, upgrades to receiver design, or just anything you'd be wise to watch out for on the used market.
If you have multiple classic weapons (no long rail on bottom) that they offer mounts for, assuming you want to be able to install the 203 on them, it might be the way to go.