I have a smart phone/pda with Bluetooth and a Bluetooth GPS receiver and memory map 1/2 mill (which includes the 1/4 mils in the coverage). Haven't tried it in the air yet but works brilliantly in the car and I like the familiar mapping. Main prob is mounting . I am going to try blutac. The GPS was under £35 . The PDA clips onto my kneeboard. I am a student at mo. so won't be using it but nice to know it is in my pocket if I get well muddled.
Don't wish to offend mods with web link but pm me anyone who is interested. I have no connection with the supplier