Plastic card is know as several things - Styrene, HIPS (High Impact Polystyrene Sheet), etc. Basically it is the stuff that Airfix kits are made out of, but in sheet form.
It is available in a wide variety of thickness' and sizes, from around 20 thou (0.5mm) upwards, and sheet sizes upto around 4' x 2'.
Glueing is simple with any of the liquid glues (solvents) available from hobby stores made specifically for styrene, typically being dychloromethane based.
Prices vary from place to place, but as a guide I normally pay £3 or so for a sheet of 1330mm x 600mm x 1mm.
Hope this helps, but feel free to ask any other questions and I'll do my best to answer. :)