You can expect to pay from between £500 to £2,500 for a wedding photographer.
Pay over the top and you are not guaranteed best quality, having worked in a laboratory processing photos from other wedding photographers that charge that amount, I know as I've seen the results!
Too low and they may be cutting corners. It's not just the time on the day you are paying for, its the selection and post production to get the most out of your photos.
Remember that your photographs may be the only memories you will have to look back on in years to come so do your research carefully and don't just look at price!