A free site for selected guests

I want to be able to give certain people a free site for life, so to have a kind of guest account that doesn't show up to other users who will be paying whatever rates I set. I can't see a way of doing that. Pro Sites won't let me set up an account without a price. I've had a look at coupons and tried creating a coupon code giving a 100% discount but on entering that it's still asking me to go through the PayPal checkout process and also appears to only be applying the 100% discount for the first month whereas I want to be able to give friends a completely free site.