dealerships would have it, new piece unpainted (of course extra cost for them to paint it). Or you could try other auto markets like bilal gunj, or link road etc for second hand pieces, provided they have one in your color.
For rough estimate, cover piece unpainted without side indicator (older city models) cost about 800-900 from the dealer. Indicator piece I think is a separate piece so that would have its own cost. Around 1000-1500 for paint.