I don't get these things. First off, it looks like their website is pretty much optimized to be viewed on a smartphone, and is pretty terribly to try and navigate on a PC.
Second, if you want the look of Velvia, why not just shoot Velvia? Even more so with B&W, the sensitivity of film differs than digital, so the digital conversions never look quite like the original.
The Plug-in pack is $120-- I know I'd tire of fiddling with digital files long before I got through the same number of images as I could get out of $120 worth of film and chemicals...
If you want the look of film, why not just shoot film? Film and digital are two very different mediums. If you like one or the other, use it, but it bugs me how much time is spent with digital files to get them 'film-like'.