Hi I'm on the dexcom,
It cost £500 for the transmitter and 4 sets, the receiver is my pump. If I remember correctly the receiver, transmitter and 4 sets was around £1300. 4 Sets cost £186, they last a week according to the manufacturers, however I'll have completed my 3rd week on my 1st one on Wednesday and it's still very comfortable and accurate, although the sticky has given up the game. Quite a few other people keep them in longer, because of the expense, and don't seem to have any problems apart from the sticky stuff.