To some people, yes. Personally, I don't see the difference between copy #1 and copy #362, but some may. I don't really even see the difference between a lettered copy and a numbered copy if the books are otherwise identical (there are some examples of this in Buk's catalogue - primarily in the NYG's).
Anyway, off the top of my head, you might see something like a 10% premium for copy #1, or you might not (how's that for a definitive answer?). What really sets low #'s apart is that often Buk hadn't gotten bored with signing yet, so he's more inclined to include a doodle or something extra. Then there are other times where he spaced the doodles out randomly across the numbered copies, or doodled in them all...