I am not aware of anyone being able to make quality colloidal gold with only 48 volt power supplies. Utopia Silver's Silver Bullet generator has a 48 volt power supply and they advise that, while it makes superior colloidal/ionic silver and other metal solutions which have a bit higher colloidal content and smaller particles than most home generators, it is not suitable for making quality colloidal gold.
Those prices are really high imo. If I wanted to get a home machine which came closest to the Utopia Silver and Mesosilver process, I would opt for the Organix Technologies NST-120 with DELUXE PLUS PACKAGE.
http://www.organixtech.com/pricelist.htm
The price is only $395 and I would trust that machine much more than any 48 volt generator. Note what they have to say about high voltage being essential. Note also that they use a nano-arc system.
Odd the link works for me? Not endorsing the generator mind you, just pointing it out.
You may be right about the 50 to 60 volt supply with a current capable of 800ma being just fine. You are certainly right about not needing an arc. However, if you want the very smallest particles and thus greater surface area per PPM - whether it be silver or gold - then the arc is the way to go along with a few other refinements.
Sounds like the right color. My Utopia Silver CG is a purplish red in color. And it is truly wonderful stuff - both Luella, myself and others have noticed improvements in mood, focus and memory when we take it.