Blocked Toilet Price?

My mum has a blocked toilet that I can't manage to unblock myself. I've took the tiles off around the back of the toilet and it's also dripping when it is flushed where one of the joints is on the pipe at the back of the toilet. I think the u-bend might need to come off to unblock it or might need some rods down there if the blockage is further down. When you look at the toilet it doesn't look blocked and there is no dirty water but when you flush it the water rises up to the top and then drains away slowly. How much should this job roughly cost and what does it involve?