Ah...the old "I want my artwork files" dilemma.
What to do, what to do, this is what makes this forum truly great, lots of interesting opinions on this.
Think this out for a second. You said you "donated all our time and effort in designing and vectorizing all the logos" to be nice right, kinda.
If someone donated $100 to the non profit, would they want to keep their $100? No, a donation is a thing you let go of when you donate it.
So, you say you donated the artwork but now you want to keep it. Was it really a donation?
You may actually have done the artwork hoping that the following year they used you again.
Now on the other hand, I get you bro, about all the effort and time that goes into redoing really lousy artwork for customers.
When we're done with it it's like giving brith to a beautiful thing, we fall in love with our end product (emotion).
Hey what would life be like without emotion. Not so hot. So, I fully know the feeling of wanting to keep the little artwork children I made.
In many ways the end user is NOT entitled to it. You are giving them back a file they did not give you. But if you donated it, as you said, they are entitled to it.
I say give it to them, then write forever after on every quote you give...
"We can vectorize and clean up your artwork for $200 (?) and give you a 1 time copy, or we can clean it up for free and the cleaned files remains on our computer unless
they are purchased".
That's really bad wording but you get what I mean. Lesson learned, you're a much smarter business person now, that's for sure.
BTW, there are other threads on this subject on this forum, they are a lot of fun to read.
Enjoy the Texas sunshine! I'll be in Dallas in a few weeks visiting relatives.