This is true, but hardcore shoul de hardcore, hence put only vanity and no longer obtainable ingame items in shop, nsme colors, codmetic stuff as a reward for donations.
On the hardcore side of things, just say: everyone who wants to donate, do so, with nothing in return, except the feeling of keeping the server allive. Remember: donation= benevoulous, means you give without expecting anything in return.
For the oh item x is too expendive, read above, or consider this: preety soon que skipping donations will be required for hardcore raiding, abd if you want just one item, donate now 23, 2 weeks from now 23, and preety soon you have the item server has funds.
To obnoxious: all private servers are FREE, remember that, donation is benevolous. A serve with no donaations is not a big one, but it is a tight, unite comunity