Regarding the price, the 50mm is the least interesting of the bunch in my opinion, except for the ".1" thing (and that's saying nothing about its optical quality). Pending testing, I think if I was looking for a fast 50mm with manual focus at a decent price, I'd rather go with Samyang; the 50mm f/1.4 is a solid lens optically (though not perfect) and available for just about any mount - and it's cheaper than the 7artisans. There's even an AF version for Sony shooters that's very good optically, and if you have an APS-C (or smaller) camera, you can get the 50mm f/1.2 which is a fantastic performer (though at f/1.2, it needs very careful handling when focusing). The 50mm f/1.2 is the same price as the 7artisans, and the 50mm f/1.4 AF is not a lot more expensive.
The 7artisans lens that looks quite appealing to me is the 25mm f/1.8 - not for
mainly (because there's the Panasonic 25mm f/1.7 which is not very expensive and a fantastic lens), but as Martin has said, it's filling a niche for Sony APS-C shooters. And to see the performance of the 7.5mm f/3.5 will be interesting because of another competitor, the wonderful Samyang 7.5mm f/3.5. All this pending quality, of course ...
Bottomline: New and cheap doesn't always mean fun, and brightness/speed doesn't translate into optical performance. That's even true for much more sophisticated lenses - my Voigtländer Nokton 35mm f/1.4 MC is nice enough, but capricious wide open (soft and smooth - nice to look at, but definitely not very crisp, not even at the focal plain).
M.