I havent read the entire post so not sure if this has been answered, but will the tickets be cumulutive? Like X has donated 50 euro at week 1 and have 50 tickets, donates another 50 euro and now has 100 tickets at week 2?
If so, like someone early on here mentioned, some rich(or desperate) donator person is gonna have a shitload of heirlooms after awhile.