I would add to the list... If you have an Android smart phone, how about the free app XCSoar? It's a "real" soaring app, the phones have GPS built in, and the latest XCSoar version has audio vario. If you don't have an Android smart phone, buy a Dell Streek 5 on ebay for 180 bucks or whatever the latest price is.

Warning. XCSoar is a complex, comprehensive app that needs to be setup correctly and understood or mistakes will be made. Always back GPS up with paper charts, knowing where you are visually, and doing your mental math calculations for safe final glides back home.

You can also download the PC verson of XCSoar and practice in sim mode so you learn the app before taking it in your glider. Distractions are not good for you or other traffic. ... Aaron