Sorry to say this, but this idea is nothing but trouble. It sounds nice for everyone to pitch in on your birthday, but what happens when it's then next person's birthday and you can't be there? Then it looks like you got the free ride but don't want to pitch in for others. Your friends will know it's not true but it's still out there.
Or what happens if you decide to raise buy-ins sometime before the next birthday? Does everyone still buyin for the birthday boy or do they just pay half since the stakes are doubled?
Too many things that could go wrong, and since it's your birthday you have the chance to stop it here. Say thanks guys, but here's my 10 bucks to buy-in (or whatever you pay).