Actually they look quite different in the pic's to me. Same basic design but clamps and shape are different.
Yeah, some of the shapes are slightly different, but with a design that similar chances are that the same OEM makes all three filters. The differences in the Marineland are mostly cosmetic.
Computer components are the same way; one company will make a product for two or three or four different brands. Some may be visually identical, some may have some variations that a specific brand requested-different heatsinks, different capacitors and other SMTs, slight circuit layout changes to tweak an aspect of performance that they want to either market as a feature or save some money on-but they're all basically the same device, and they all came out of the same factory.
I'd bet money that that's the case here. Even the flow rate discrepancy between the filter CWO posted and the C-220 is easily explained: Marineland rates it with the media installed, the "Perfect" unit is rated with no media, and possibly a little bit of fudge factor. Again, this is done all the time with computer components.
The other option is that it's a ripoff of the JBJ and/or the Marineland. Either way, if it doesn't leak or go through pumps and it comes close to matching the Marinelands' performance, it's worth a good deal more than what it costs.
And $40 is not implausibly low for something like this, especially if it's coming directly out of China. People would be stunned if they knew what the markups on a lot of retail products are; $40 from a wholesaler for a filter that stickers for $130 isn't an unusual markup. If it were $19.95, I'd be skeptical, but $40 doesn't set off warning bells for me.