I’m gonna assume you forgot to pad the $4.95 price tag to that for APRSDroid. After all, everyone loves to support developers.

$18 dollars for the cable and $5 for the app. You can donate more if you find it useful, but I wouldn't ask anyone to do that right out or the gate. It would be great if you did though, especially if you get use out of it.

Wait, what? HT to HT?

Maybe I worded that poorly. That podcast was great that you linked. But I guess I still have a question. You can still go directly from one radio to another with APRS, can't you? It doesn't actually need digipeated, does it? It was pretty clear in the podcast that APRS doesn't have close to the range if FM voice, so maybe the small range makes it a moot point, even if it is possible. I didn't mean to suggest APRS would be digipeating at all if you're going "HT to HT". Maybe I should have said if my APRS packet from my HT is heard directly by your HT.

Apparently the Kenwood TH-D72A has built in digipeating capabilities. What the hell. That’s somewhat scary.

This little guys looks great for APRS, and I would love it for that. To OP's question though, the price tag might be prohibitive

Get an "APRS" cable. May then need a 3.5mm TRRS adapter to separate mic/speaker ports. Use VOX for PTT.