No one in New Zealand gets dexcom for free, not even children or pregnant women. Just hope dexcom in your area doesn't use the same captcha system as NZ to allow you to log into your account... (30 minutes of attempting to choose pictures with lorries and bikes and I still couldn't do it.) Luckily it now seems to let me buy without being logged in so I just avoid the login process.
Good luck with your investigations. (Am presuming that they are allowing you to buy after creating an account?) But I recommend ringing dexcom and speaking to a human if the website is being too unfriendly. Their customer service is good.