E30 replacing power antenna with mast

[jleppo]

I have an '88 325i that the power antenna snapped off when a piece of Masonite blew over my car on the highway and clipped it off at the bushing.
Rather than replace it with a new power mast, I'd like to take out the motor unit and replace the antenna with a non retracting mast antenna. I found a good thread on replacing the motor unit with a Z3 antenna base, which appears to be the easiest, but of course it's the most expensive and most difficult to find (the Z3 antenna base). Also, I looked at the wiring going to the power mast, and it looks like a sadistic electrician's nightmare.
I also found another thread on another forum about installing a Metra antenna base, however there are practically zero details on the wiring and what connects to what (Which is what most folks would want to know, I think).
I have an after-market Pioneer DEH-P2600 head unit that had been installed by the previous owner, and for now it's fine for my purposes.
What I'm looking for is:
A) an inexpensive solution (like under $60), preferably something universal and easy to find.
B) The specific parts needed including any mounting parts, and instructions.
C) How to wire it, what to remove, what to leave in, what connects to what, in enough detail that a fairly mechanically inclined but electrically fairly clueless person (moi) can follow.
D) Ideally it will be some sort of base that will accommodate just about any screw-in mast - I have a short rubber mast that's pretty decent, or I may go to a shorter stubby type.

Thanks, all!