The idea of bringing in extra money to pay for your servers, is very good, but quite expensive... 10$ a month for the lowest level seems pretty overpriced. I know we see a lot of players running around with coloured name-tags, but the numbers of them will probably thin out... Nobody wants to pay over time. People of course will, but perhaps it might increase your sales, if you made it a one purchase, lifetime. However, make this an additional option to the current, and make the single purchases $100.00. Then the people who think they will play for 9 months or less will buy monthly, and the players who think they will play 10 months or more can go for 100$, and have a permanent. Not many people will pay 100$ for a Minecraft server, and fewer still will actually play on the survival games for more than 10 months. Therefore, a few people will spring for 100$, but probably not play for 10 months.
So:
$100 = Lifetime Iron
$125 = Lifetime Gold
$150 = Lifetime Diamond
As you can see I have just added the extra price from the higher ranks (monthly) to the higher levels... Perhaps these should be doubled so:
$100 = Lifetime Iron
$150 = Lifetime Gold
$200 = Lifetime Diamond
Tell me what you think! If this does come to pass then I will probably donate.