Guys, I will shop both eBay and Amazon... I think I found the in-dash meter thru eBay. I ordered directly from the vendor thru eBay using Pay Pal. If the vendor has an okay record, and the ones I have used always do, since that is one criteria for me, they usually do fine with delivery. It looks like mutlitple vendors will list the same device, so you takes your pick. Delivery usally takes a week or two, (maybe 3 weeks in the case of one item, but the price was so low, it was almost free) but obviously China subsidizes the mail, since shipping is often free for the buyer. I have ordered perhaps 12 items that way, and each purchase arrived in fine shape, working, no problems. If I get something that goes wrong, for the price, I will continue trusting until I have a run of trouble. Keep in mind, much of what I order this way is not readliy available locally: I have to order it from somewhere. Since it is made in China to begin with, why not order it from there?
Wiring it: a red wire goes to any (switched, of course, since you don't want the thing on 24-7) power source, almost zero drain, so the source doesn't matter, and the black wire goes to any ground. Done. If it will sit exposed, be sure to get a "waterproof" device. I used a tiny bead of silicone sealant around the meter so water couldn't get behind the plastic dash.
For the price, it is a worthwhile indicator of potential problems with your alternator or battery, IMHO. I got the lighter plug in meter when my car had battery issues (well, after I had battery issues...) with the idea that in the future, it would be easy to monitor such potential issues.