As far as what your insurance policies are, you really have to call them find out directly. The insurance companies, and different policies are so vastly different.
But I'll tell you what I've been doing. Yes, the CGM sensors are VERY expensive! I started them recently, and even with the insurance paying 80%, (which mine does) it can get costly replacing them every 3 days, as Minimed wants (sure they do). A friend has the Dexcom and though they are a bit cheaper and per the FDA can be worn 10 days, she tried wearing them longer and can get a month with no problems. So I tried with the Minimed sensors, and I also can get a month (if I'm very, very careful not to pull the sensor out when I disconnect the transmitter to recharge.) I also take care to keep the area clean, and cover it with IV pad, (which I buy online.)
As for strips, are you buying them online? I buy the One Touch Ultra online, and can get them as cheaply as $25 for a box of 50, (I pay twice that at Costco.) Then I submit the receipt to the insurance company to get reimbursed for their portion. Like I said, all insurance companies are different, but call them and ask what their policies are with regards to buying supplies online. The number should be on the back of your insurance card.