You can find 1 gallon counter tops for as cheap as $80 and all of the 1 gallon table top units are throw aways; they may last 5 years or if the electric spikes, they may last less than a month because of the fuse in the electric line.
I prefer a 5 gallon or larger in line distiller and if you spend much $$$ always buy from a website or company that you can call and call in your order and make sure they carry all the spare parts for every model.
We use the waterwise, but I assume all larger companies are just fine.
You can e-mail me about any of the books in the 2009 school folder, they are all pdf files and should be easy to fine. There are about 30 people with access to that folder.