They have good prices and looks like a good service.
If you purchase a kit from them PLEASE note that Sodium chlorite will destroy the rubber in the dropper bottles! Even if you are super careful to not let the solution get in the rubber bulb, it will eventually destroy the rubber.
My favorite bottles are these plastic ones that provide a measured drop. The green bottles Humble uses do not provide a measured drop and need to be controlled carefully to not get more than you want. These are LPDE plastic: dropper bottles
I have bulk powder, but have only been selling it locally (Olympia, Washington). Contact me livegr8 at gmail.com with MMS Curezone in subject if you are nearby.
Most health food stores or food co-ops carry Citric Acid (used for cheese making and canning). Keep it in the fridge or make a new batch regularly as things will eventually start to grow in it if left at room temp. We leaves ours in the cupboard but make a new batch every few weeks.
Also, when you make MMS from powder, put it though a coffee filter. Just use a filter from a Mr Coffee and put it in a larger PLASTIC funnel to hold the filter. Filter into a glass canning jar. It will be a yellowish color.