"We always get this question, when is too small, too small?"That’s David Rauenzahn, chief school administrator in Avalon and Stone Harbor, responding to a question from the Star-Ledger about the total comparative cost per pupil in teeny-tiny districts like the ones he serves in Cape May County. Avalon, all of 77 kids, spends $32,384 for each one. Stone Harbor is a relative bargain with 80 kids and a cost per pupil of $23,698. Then, of course, there’s Sea Isle City Elementary with 66 kids and total cost per pupil of $35, 983. When is too small too small? Right now.