Hey,
I suggest making it so you can simply send Bitcoins to an address rather than using coinbase for each ticket. And then you'd simply send the winner's address the pot. Also, you should look into making this provably fair. At the moment there is no way for someone buying a ticket to know whether it is fixed or not.
Best of luck to you, if you make these changes you'd see a lot more ticket traffic I'm sure.
I have made some changes to the way it works and right now what I have is a form that a person can fill in their name, email, and wallet address. Then I can send them a personal wallet address to send their Bitcoin so that I may identify them and how much they have sent. The other methods I have used have either taken too long or just sucked in general. I'm not exactly sure how I can show that its fair like you suggest. Ideas?