In rec.aviation.owning Martin Kosina wrote:
: Hi all,

Hi Martin, been away, hope you see this.
snip
I had a used M3 installed in my Cherokee last year. Installation cost
including IFR cert. and filing paperwork was about $300. I paid about
$1200 for the GPS and the Mid-Continent CDI. Of course, I made the wiring
harness myself (which I am capable of, and had the proper equipment to do),
and this saved me some labor.

I picked the M3 because it had the simplest IFR install of all older GPS
units. (And because I have a BMW M3.) The King units need a very expensive
CDI with a resolver in it, and an external switch annunciator. The KLN89
moving map is not very usable, at least to me.

The database support for the M3 appears to be likely to continue for a while.
I've been using Skybound for updates with no problems. It appears that some
of the other older GPS units are getting marginal in their datacard capability
with all of the new GPS approaches and intersections - look at the Jepp
"NavData" area for their announcements about Apollo 2001 and Trimble/Free
flight datacard limitations.

If you want a slightly newer technology unit for a reasonable cost you
can look at the Garmin GPS155XL, or the UPSAT equivalent (GX55?)

Hope this helps,
--
Aaron Coolidge (N9376J)