Totally out of pocket budget at least $6,500 per year. I believe that a box of 3 sensors alone (30 Days is about $500). Then you still have to buy the transmitter even if you use an approved phone rather than the Dexcom receiver.
If You have Medicare Part A&B you should have no out of pocket expense as Dexcom has to send you a monthly subscription which includes sensors, transmitter, lancets as well as a starter package which includes a contour next meter kit, initial transmitter, receiver, etc.
If you have a moment read my first post:
Hack Dexcom issues by doing this - Updated 8/2019
That should give you a lot of insight into the process. Let me know if you have any questions.
I have been checking around and do see sensors are available at a discount down to about $279 for pack of 3 G6 Sensors.so you may be able to shop around and get into this as self pay for as little about $5,000 all in with transmitters.