I disagree with the other posters. You don't get what you pay for with filters (although you do get crap when you pay $12 for a filter). When people have done actual proper tests of filters, price was not a variable in a direct relationship with performance or quality, so long as you eliminate the $<50 group. With filters costing >$50, people use stuff and have anecdotal opinions that rarely are calibrated to additional personal experience with the other brands.
And this case is a good example. I too saw the Zomei filters and bought a 1000x ND filter. Coincidentally, I bought a Breakthrough Photography ND filter too, of a different intensity. It's apparent that these are made by the same company. I suspect Breakthrough uses Zomei, or a common manufacturer. There are several very unique elements to their constructions, such as a flat outer metal ring concentric to the glass filter, on which label writing is printed. The bevels are quite stylized and almost identical. Performance wise, they are both decent, although I only have a few days in the field with them. I believe the Breakthrough brand brags of more coatings, so they're not actually identical. (Edit: looking at the amazon link the OP included, this is likely a different Zomei filter than the one I purchased, which was cheaper and didn't advertise any particular coatings).
Actual data on the Zomei (polarizing) filter by a respected third party source:
http://www.lenstip.com/index.php?art=139&roz=24
That same source indicates (rather convincingly) that the best filter/price (for polarizers) is the Hoya Fusion Antistatic CIR-PL.
http://www.lenstip.com/139.16-article-Polarizing_filters_test_2015_Hoya_Fusion_Antistatic_CIR-PL.html
You can spend more than twice as much on a B+W filter that is demonstrably worse. The B+W lineup of filters is quite good, but the more expensive ones are not necessarily the better filters. In an analysis of performance versus price, the best value B+W filter (Circular-Pol MRC) came in 9th out of 23 filters.
When Lenstip did this same analysis a few years back, they found that some of the most expensive filters were actually the worst. Interestingly, their 2015 data shows that the most egregious examples have been replaced by better performing filters, perhaps because the manufacturers are now dealing with better informed public.
In sum:
1) It's smart of you to ask the question on the forum, and don't let people tell you to go on price as an analog of quality
2) It matters what filter you use, with about 1/3rd of filters being very similarly specced on the high end, but with quite different prices.
3) Zomei would be a kickass filter if it had coatings, but it doesn't. I like mine, but I know what I got for very little money, as a backup filter. Breakthrough Photography filters appear to be coated versions of the same or similar filters. The going is early, and we don't have measured performance, but they might be chart jumpers when Lenstip gets around to doing their data analysis again in a few years. That last bit is speculation on my part.
Finally, I think it would be great for some organization to develop some specific criteria for ND filters that could be used as a standard actual metric of performance. You could have three variables in addition to light blocking level:
- Min/Max consistency of level of blocking across lens
- Light scattering properties
- Color introduction
These are measurable things that would cause manufacturers to up their games if they knew the market was expecting these figures. And, of course, they would become comparable. MTF charts have been great for lenses, and they're even bs-detected by people like Sir Roger Cicala, with their own equipment. One can dream.