So, it started as a "joke" in cc, but after thinking about it a bit, it can actually be a good concept. What if once a year there is a "sale" on ecash with a decrease on the purchase amount for donators and maybe a bigger percentage off the purchase of ecash for new donators. Maybe buy one , get 1/2 off second one.
Another idea would be to have a "shop sale" I think this would also encourage people to donate and buy items.
Both "deals" do not necessarily need to happen on the same day, but maybe have it schedule as a yearly deal. Once a year ecash sale and also once a year shop sale. Something for new people or regular donators to look forward to and some donations or purchase better than none :)