I'm assuming you mean a Blood Glucose Testing Meter

If so the meter itself can be anywhere from "free" up to about 100 dollars (USD)

I have never paid for one, most of the companies will give you one free if you buy a pack of the testing strips - those are what cost the real money over time

They go from about $30 to $100 for 100 strips depending on the brand

Many insurance companies will cover the cost of the meter and a couple of strips a day if you get a prescription from a Doctor or you can buy the meter and strips from most drug stores if you want to pay yourself