They all seem to be about £80-90 ish. Read the small print very carefully. There are more things they won't cover than things they will.
For example, mine doesn't cover any damage resulting from the use of a ladder! Thats pretty standard in these policies but not much good if you are a window cleaner.
Realistically, what damage are you likely to do? Most of my damage has been broken flower pots. The only thing I'm scared of is if someone trips over my hose.