I guess the first question I have is whether you want to buy a complete, ready to use gun or one you put together yourself? And if the former, do any of the pre-made guns suit your fancy in their form factor?
Also, anything "Sinden" will have the white border. That border is a trade-off for the need to place 2-4 IR LEDs around your monitor. But if you don't want a white border (which reportedly doesn't work too well with some monitors) then you'll need the IR LEDs.
Personally, I think the IR solutions using the sensor type found in the Wii controllers are the best solutions, as they are accurate and I not only dislike the border, but I also don't care for the idea of needing to adjust the screen for optimal tracking, rather than optimal game image quality. The ones using the IR/"smart camera" tech would be the SAMCO updated to
IR-GUN4ALL (FREE and Open-Source),
GUN4IR (pay for full functionality), and
Lichtknarre (FREE - Software under development, but very usable in it's current state) which uses an actual Wii controller, making it wireless and convenient if you don't mind using one of the many gun shells available for them.
As for the Chinese guns, the price seems to be right, but it's hard to know what you are getting. They almost certainly use an unlicensed copy of the GUN4IR firmware, and if that's the case, you'd probably additionally need to pay for a license to get the software for easier setup and use and maybe even require a re-flash of the firmware. There's also the possibility that they could use "knock-off" technology of the type used in 3rd party Wii controllers which can be inferior to the original. But you'd need to take one apart to know for sure.
Regardless of which direction you go, there will likely be considerable effort required on the software side. While some are easier than others, none will really be "turn-key" like buying a backward compatible PS2, GC1 and GC2 and all of the available lightgun games for true CRT lightgun gaming. This is still the epitome of the experience, but the library is more limited and can be much more costly and difficult to complete the collection, given the rarity of some of the titles.