never buy less than 750ml.
and never buy anything but Ketel One
I usually buy 1.75L bottles, but on rare occasions that I have 750ml, we get a decent amount of shots.. are you talking about shots like.. shot glass hammer it back style or mixed drink style? Everyone pours differently but you should be able to get about 15-17 drinks out of the 750ml I'd guess.. and about 10 from the 350.
we free pour and go at least double shots in drinks so I don't know if I'm on target or not..sorry.