Opinions appreciated. So it looks like the transponder (certified and used) is being listed for about $2,450 on other sites. And the 3i is typically priced about $375-$400. This is the entire kit minus the external GPS antennae. I'm guessing it's worth listing at $2,950 and take the "best offer". New it's about $4k. Of course, it's worth exactly what someone is willing to pay for it. I'll mull it over for a few more days and maybe repost. I really liked this transponder and enjoyed getting traffic on my iPad. The automatic switch from Ground to ALT is nice, too. But having it mounted in such an awkward place in my panel was odd. The yoke cross-linkage prevented it from being mounted under the avionics stack and there just wasn't any other place to move it.