Parts are available from Kiyani Autos (Gawalmandi, RWP) and Mitsubishi motors (Saddar near hathi chowk). For used (kabli) parts, mithoo khan ka ahatha is best for engine parts or sultan ka khoo (besides PSO pump) for body parts. I own three lancers and never been into much trouble with finding spares.
Drive safe and u won't regret ur decision buying a Lancer.