Well those who don't want to spend money or don't think of donating anything. I will advise them to go to their work and volunteer for a month and that too would not even be 10% close to what it needs to make a model.
I make models for myself and because I like to make them. Money is not what I make them for however there are times when its is really good if few bucks are dropped in. Making a model and testing it does consume not only time but other resources and when someone contributes its like you help a friend make something the only difference here is, you can't give your time so you shed a few bucks of yours.
I am building Su-27 pit since a year now have reached only 20% of it and don't know when I will get it done. You can't imagine how much time it takes.
Regards,
CombatAce