Hi Susie, appreciate you have found info on the libre, but I can speak better from the point of view of the Dexcom, as this is what I have. The Dexcom G4 integrates with the Animas Vibe, but is standalone, and can be purchased as 3 separate components, the sensor, transmitter and receiver. It is also possible to use it without the receiver as the display, by purchasing or building an xDrip, and using a mobile phone and/or smart watch as the display.
@CapnGrumpy is correct in that it is not cheap, but this is subjective, and for me the benefits outweigh the cost, many times over for me.
If cost is important, then by looking at different suppliers across Europe and carefully tailoring the solution, you can be up and running by purchasing (approximate prices in brackets) 1 sensor (£60), 1 transmitter (£220) and 1 xDrip(£55), and then an ongoing cost of £60 every 1 to 4 weeks for the sensors.
The ongoing cost is difficult to estimate as sensors are only guaranteed by dexcom to last 7 days, but I routinely get upto 4 weeks out of mine. Additionally, you will need to buy a new transmitter every 12 months approximately. Each person has there own views, and many seem to prefer the libre, but I have found the Dexcom accurate, customisable and most importantly calibratable. Hope this helps.