Calculating expected value (not homework)

[AyashiKaibutsu]

So having a raffle with range of prizes (of differing value) and a set number of people entered. Want to offer the ability to buy more tickets and trying to calculate the expected value of each additional ticket so we can find a reasonable price for the additional tickets (price of original ticket and number in existance is already set(it's the ticket for a party)).

 

[DominionSeraph]

depends on how many are bought...

 

[wiredspider]

d) Not enough information