Depends a lot on your nonprofit's structure.
There are various types of supports one might give depending on time frame between support, if it is one-time or recurring,...
One may use Patreon for inspiration on various levels of payment and their associated accesses/benefits. These levels will help you treat each supporter the same way.
That being said, I would first of all clarify the overall support structure and the various types of support people might give. That way you'll make sure no-one gets upset for being treated differently. This might also help get more people involved, depending on the benefits one might get from supporting your project and what one seeks.