Hi,
@Jackie100 , I don't use G6, but when you're sizing up the prices, G6 "officially" lasts for 10 days, but there are ways of resetting it to get longer, like 2 or 3 times as long. There's been a few threads about it on this forum and plenty of stuff through google, for example:
http://www.ardensday.com/blog/dex6restart
It seems to be more difficult restarting a G6 than a G5 but that'll maybe change as time goes by.
Also, if you use, not the official dexcom app, but an android app called xDrip+, it'll let the transmitter run for a lot longer, sometimes twice as long, than the official app, so you're not forking out for a new transmitter quite so often. At least, it did for G5, not sure about G6.
xDrip+ isn't official in any way. It's a use at own risk gig. When dexcom first came out, people liked it but thought the app could be better. So, a charity called Nighscout Foundation built their own, dexdrip, and over time it's turned into xDrip+. The alerting systems are more advanced, and it has things like predictive simulations which dexcom would take years to get past the FDA.
https://jamorham.github.io
I've been using one of the libre add-ons, a blucon from Ambrosia Systems, for over a year now. It was a one off cost of about £100. There's another newer one, miaomiao, about £160.
They can look quite large when you see them in photos, but in reality, they're really not that big. The blucon is a couple of millimetres wider than a libre sensor and about the same height as two and a half sensors on top of each other. It's about the same height as a G5.
I notice it about as much as I do the libre - not at all. I tend to wear long sleeve shirts, so it might be an issue if you're wearing shorter sleeved stuff.
The blucon links up with xDrip+ so I'm getting dex style alerts.
Maybe worthwhile googling your area's ccg. Some of them publish a lot of policy info about stuff like libre prescription. I'm lucky enough to live in an area which prescribes libre to any T1 who wants it, so, for me, free libre, 100 quid for the blucon and free xDrip+ was a no-brainer to get cgm without the cost of dexcom. If it looks like your area might be going down the prescribing route, it might be worthwhile considering the add-ons, but it is really still a postcode lottery.