I agree wholeheartedly with B K. In hiring a professional, you also pay for the fotog's assistant and use of expensive equipment, knowledge and understanding of light, and time spent behind the computer after the special event, tweaking images to render maximum color balance, and enhancing features of the subjects and that takes knowledge, talent and experience that comes after years of practice and training. But, in short, you pay for what you get. Top dollar (rupees) usually goes to the better fotogs; true, some fotogs aren't worth what they charge but that is up to the person hiring to check and scrutinize the fotog's portfolion, which should be an indication of his/her abilities and skills, and to also compare with other fotogs.
Wedding photography is not the easiest type of photography. A well-trained, qualified, experienced fotog will also KNOW how to pose individuals and groups... to minimize undeserable features (like a double chin, someone's nose that is a tad too large, or protruding ears, or someone who's overweight or bowlegged). THAT is skill on the level of an artform, and one doesn't develop this skill overnight; it takes years to develop. Also, a skilled fotog will also know how to direct subjects for portraits using subtle tones and words to ensure no one feels offended. Remember this last detail; it's very important.