Here is the model that I bought and am very happy with:
http://ultrasonicsdirect.com/shheuljeclst1.html
($198)
I can make 3 batches at one time in it which I then pour into old Perrier 750ml bottles and store in frig for the week - which for me is plenty. 3 batches uses up one and a half Perrier bottles. I drink about 4-6 shot glasses of the mixture every day.
One of the reasons I prefer this US machine over the first one I bought from Harbor freight ($30) beside the fact that the small one could only hold one batch is the cleanup. The small one has plastic that catches the drips and you cannot get the mix out of it after a while. Eventually, I imagine, it will short out.
The recipe:
[Keep in mind that I triple this for one batch in my larger US machine.]
Ingredients:
1 tablespoon ascorbic acid (aka AA) (if you want to skip the buffering process buy sodium ascorbate instead of the ascorbic acid) (Pure Bulk online site)
1.5 teaspoons aluminum free baking soda (Bob's Red Mill) (local natural grocery store)
3 tablespoons nonGMO soy lecithin granules (if you want to avoid soy, get sunflower lecithin and use 1 tablespoon) (local natural grocery store or online can find NOW brand)
distilled water (I make my own)
Process:
--4 ounces distilled water and the AA go into a blender (or use stick blender)
--add the baking soda a little at a time until the foaming calms down and then blend for a minute. (you are trying to get a neutral pH here so you may want to use Ph strips to be really sure)
--add 8 ounces more distilled water and the lecithin and blend again for 2 minutes
--put into US machine and let run for 30 minutes.
--pour into dark glass bottles (old wine bottles work well)
One shot glass is about 1.5 grams of C with this recipe) I have taken a whole 750ml bottle of this in a day and not had any bowel problems, which you cannot do with plain AA - you will get diarrhea.
This group is a great source of ongoing experimentation and help. The people there had done this with Glutathione powder and other antioxidants as well.
http://health.groups.yahoo.com/group/DIY-LET/
Let me know if you all have any questions.