Take a look at the Nexus 7 WiFi - less that 100 bucks - great in sun light - running XCSOAR (I actually run TopHat by Rob Dunning - a new interface for XCSOAR - which makes the display and loading the site files simple even better)

you will not be disappointed and you can reach out to a bunch of people to ask questions. It is an powerful setup - and take 10 minutes form install to using it in your glider, promise

WH1