Why don't you use your 35 for a quarantine tank? Put a few cory cats in to keep it cycled and a good clean up crew.
Other than that, small fish. Tetras, etc.
I must say though,, it sounds weird that "many" people don't want to give you their fish. So often that you're tired of it? How do people find you out to get rid of their fish, then decide not to? Something smells fishy. LOL
