Gee, I would have laughed and said, you've never seen my apartment, it would cost an
arm and a leg in time and copying to get my "entire" collection!" and then smile, and then say nothing else.
Unless it's a loved one or a family member, just the practicalities of an entire collection is ridiculous.
If he comes back to you, you can say, I thought you were kidding, and I'm so flattered but the logistics are impossible (re above).
Now I'm annoyed at your behalf!