Frank the Tank
Good, I strongly suggest you download and save forever the schematics and build diagrams. The reason I say this is the Governments of the world do not wish us to have this technology and will eventually outlaw it so it's best to have that technology burned to permanent storage for use when you need it.
Don't build one unless you can solder like an expert, build and create perfect prototypes on the first try. I spent 20 years in the high tech industry and no one is able to get it right the first time. It usually takes 10 builds to get an acceptable unit. Even then it's still a prototype and prone to failure.
You can search this board for units or go to eBay. I purchased mine from this seller at eBay for $100 during a bid auction. Don't just buy, bid and limit your max bid to $100. In a week or two you will have one of these units. You may even get one for $80 if you can wait.
I used the unit 2 hours a day for 6 months. On month 5 the silver generator went out. I contacted Smoke Research (the one listed above and they repaired it for no charge!) I did have to spend $5 for shipping.
I'm what you call a heavy user of the unit. I've dropped it at least 20 times and it still works. Worst that happened is the battery connections broke loose and I bent a connector.
Last, go get an inexpensive soldering iron at Radio Shack or where you can find one. Get some medium quality solder to use with the soldering iron. I also purchased 100 feet of 18 Gage speaker wire (you need multistrand wire, not solid wire as solid wire breaks in two days) and two connectors for replacement parts. Get some heat shrink tubing to protect the wires at the connection points.
Reason I say this is the parts that will fail will be your connectors to the unit, wires and connection to the stainless probes. They will fail due to being bent over and over and have to be over hauled. I usually have to repair them every 30 to 60 days. Pain in the ass but the support is great!
Hope that helps.