So generally, as a sort of unwritten rule here, we raffle out 16 slots. Obviously you can do as many as you like, but generally people take the last character of an upcoming block's hash. There are only 16 possibilities (hexadecimal) the last character can be, which is why we have 16 slots.
So if you want to sell something at say 2BTC, sell one ticket at 2/16 BTC
Note that a high raffle ticket price (say maybe >0.05) will make it difficult to sell all your tickets quickly.