I'd say the most obscure title can sell a couple hundred, even if its just friends and family. If tens of thousands of titles sell several hundred each it all adds up.
If this were true across the board an author like Stephen King (for example only, I didn't ask him) would say his sales last month were more than half e-books. Publishers are very stingy with their sales numbers however individual bestselling authors who I have in fact asked, report e-book sales are presently somewhere between 1% and 3% of print sales. So something is out of whack here.
As a writer myself, I've paid a lot of attention to this issue over the years. Based on many discussions and observations, I'm comfortable saying that the vast majority of self-pubbed authors can only dream of sales in the hundreds. I believe most are in the dozens, if that much.
And yes, publishers are very tight-lipped about sales, but maybe some significant author will step forward in the near future and actually put a percentage number forth on e-copy vs. hard copy.