The first-ever sale over the Internet? A bag of marijuana:
[According to] John Markoff ‘s 2005 book What the Dormouse Said: How the Sixties Counterculture Shaped the Personal Computer Industry … in 1971 or 1972, Stanford students using Arpanet accounts at Stanford University’s Artificial Intelligence Laboratory engaged in a commercial transaction with their counterparts at Massachussetts Institute of Technology. Before Amazon, before eBay, the seminal act of e-commerce was a drug deal. The students used the network to quietly arrange the sale of an undetermined amount of marijuana.
For the first pizza delivery ordered by a computer, see this footage from 1974.
The Dish 