In the interest of getting a higher frequency of donations--the value of donations should be higher [i.e. bring down in-game shop prices], or the cost should be lowered. Either way existing donors should be compensated the difference. I genuinely think it would make it more attractive to support financially as currently it is quite pricey for not a whole lot of value
It would be wise to do this while in early beta so that there's less of a backlog of corrections to be made. That way when the larger player base floods in there will be a higher frequency overall resulting in greater support