If members were able donate crystals to alliance such as 5k, 10k, 15k or any amount . It would be easy for alliances to get any pro beast easily.
On the total crystals , the alliance Leader can decide which beast to buy or number of pro pals for the alliance.
Example- A Phoebe beast of level 1 costs 20000 * 25 = 500000 crystals.
So once the alliance gets 500000 crystals the leader can get the Phoebe beast.