I've been making and selling the CrushGrind style of grinders for 3 years now, I really like the design, and I have even created several of their Mini mills.
There are three issues you'll run into, from my experience with CrushGrind...
1) While you can buy standard CrushGrind mechanisms on Amazon, and I believe they also still carry them at Woodcraft (you'll need to look at the bag, it's not sold under the CrushGrind name at WoodCraft), and that's ok for single kits. If you want to get the best price you need to order from the North American distributer in Canada. You also won't be able to find the Mini kit anywhere but at the distributer. I usually order at least a dozen kits to offset the shipping costs when I order from him.
2) You really need to use Metric drill bits for at least some of the boring. In my experience, the fit of the mechanism isn't the best using Imperial bits. Most grinders will need 4 bits to complete, and only one of the bits needs to be metric, so it's not such a big deal.
3) You really should cut a grove inside your mill for the snap fitting on the CrushGrind grinder mechanism, there are ways of doing the mill without the groove, I made my first grinder using the glue in method, but the grinder assembles better, and works better with the groove.
I've got nothing against the Chef's Specialty kits, in fact, I've been meaning to try them out, I actually think having the grinder adjustment knob at the top looks good with some grinder designs, but I still also like the CrushGrind mechanisms...
Do yourself a favor, whatever size grinder you make, get yourself a carbide forstner bit to bore out the main shaft of the mill, they just cut better and stay sharper for longer, and most importantly don't get as hot. Unless you like smoking up your shop
The other thing I'd recommend studying up on, is learn how to maintain the sharpness of your forstner bits, it will save you money and frustration!
I think learning to make Spice Mills has really made me a better woodturner overall, hope you have as much fun making them as I have!