Well, I've taken the plunge!
I ordered my MEX-BT3700U from
Crutchfield.
I *might* have been able to get it cheaper from somewhere else, but
Crutchfield had an offer that includes a free microphone ($30 retail), and I called them and the guy was willing to send the wiring harness for my 99 Prizm, but the install kit and the antenna adapter for the 2000 Prizm. I also saw on the order list that he put MasterSheets for both the 99 and 2000 Prizms.
That level of customer service was worth the extra money (if it indeed cost me any)!
I'll let you all know how it goes!
Thanks for answering all of my newbie questions!
My first thought was to have Best Buy do it, because "everyone" gets their car stereos installed (everyone I know, anyway).
But when I started looking at what's involved...I think I should be just fine doing it!
Time will tell. If I really shit myself trying to do the install, I can always hang my head in shame and have a local shop do it.
But I don't intend to have to resort to that!
I'll check in again later!