Doug
I think it was your post I responded to on the gliderforum, but will
repeat myself here, just for you! First, there are units you can
purchase for your airplane for under $300 (AK450 I think?).

Be careful of the TSO approval for what you buy as it has changed. I am
thinking the new rating is TSO-C91a. You can keep a TSO-C91 ELT for
now, but cannot transfer one to another airplane.

Craig K