The subject pretty well covers it. I do not want to tell them too few and have to wait to get the extra starters, nor do I want to tell them too many and have them order too much. Like Goldilocks, I want it to be just right.
The FLGS is asking for preorders, how many should I order?
Three if you want max copies and to play competitively at all.
the general consensus is that 3 copies of a card will be a play-set and that it is likely there will be 1 copy of some cards in the core set.
if Netrunner is anything to go by then many of the cards with 1-2 copies will be the really strong cards (astero script,san san, account siphon) so i would advise at least 2