I wonder if the actual key switch is broken? As in, the electrical contact made when you turn the key all the way? If you're up to it, you could try to take it apart and hot wire the switch to see if that will start the car.
2000 GTS 6-speed. Performance Mods: Apexi Power FC, BC Racing DR coilovers, Injen CAI, Catback exhaust, EBC 'USR' rotors, Hawk 'Street/Race' pads, Stoptech brake/clutch lines, Castrol SRF brake fluid, Exedy stage 2 clutch, Mishimoto radiator, Moroso oil pan, 11# flywheel, Braille 11.5# car battery, Energy urethane suspension/motor bushings, BFGoodrich G-force tires.