I bought a Pharos GPS Phone 600 several months ago and use it with the Garmin Mobile XT application. It works very well. I want to get a Blackberry and use the GPS on it without a data plan. I gather from reading the numerous posts here that this might be possible, but I would have to download maps to the device. Do I understand correctly that everyone that is doing this having to find maps elsewhere, that there is no company, like Garmin, Tom Tom, etc, that just sells maps on a micro SD card that can simply be loaded onto a Blackberry device?

You can use GPS without data, but you need a BB data plan for most of the map applications. There is a Garmin BB version. Please look at the yellow sticky at the top of the section. It has reviews of most of the map applications and I think Garmin is included.

Also, you can use the SEARCH function.

That's correct. There are a couple of options (neither recommended) in the "All Known GPS Apps" thread as Dubdub said.

MobileTracker and TopoExplorer (both from Skylab) work fine on my Curve without any data coverage.