As far as I know, Notes on Some Sinhalese Families have not been reprinted yet, and very few copies are in existence. The series was edited by P.E. Peiris and none of the many books he authored from 1908 up to 1950 have been reprinted. J.C. VanSanden's book -The Chieftains of Ceylon(first published in 1936) was reprinted by Navrang of New Delhi in 1994. If Vijitha Yapa doe not have any copies left you may try Navrang in New Delhi.There is also the possibility of it being available at the Lake House Bookshop, as the reproduction was done in collaboration with LHB.