Baby Bear, I don't think you have provided enough information for the most useful advice you could be given.
Are you going to be flying in a club glider, in which you will take your own equipment with you, or a privately owned glider of your own, in which you can install whatever you want?
Are you looking for equipment with self-contained batteries, or can you feed the units from an existing battery on the glider?
If the things are going to go into club gliders, how are you going to hold them in place so that you can see and use them?
It is not only a question of the equipment itself, there is also the need for connecting wires with the right terminals, and a DC/DC transformer if you need to convert from a 12 V supply which runs the logger to a 3.3 or 5.5 V supply which runs the display unit.
For what it's worth, my display unit is an iPaq 3850, which gives a good sunlight readable colour display. You can buy them second-hand on eBay.
If you are prepared to spend the money on an EW logger, why on earth not spend a small amount extra on a Flarm with logging capability, and have some protection against collisions as well? (Gliding collisions cost 20 lives over a 23 year period. It is one of the big three hazards in recent gliding accident records.)
You can download free gliding software rather than spending a lot of money on commercial packages. Displayed on a PDA such as the iPaq, these things show moving map, give airspace alerts, and display/calculate other things which are useful for gliding.
Hope that helps.
Chris N