In my area I'll probably never need to fly through any airspace where I would need a transponder. There is no "B" airspace in my area and I can fly over or under the "C" airspace if I absolutely have to go through it. Oldfox has a different circumstance since his home field lies inside "B" airspace. I may see a need for one sometime in the future but for now I can't justify the expense for something I may never really need. I read recently that 75% of pilots never fly into controlled airspace. It all comes down to this. If you're going into "B" or "C" you need a transponder. If not, you don't. James Thomas