Plantagenet Y DNA should not be hard to find considering the number of contemporary descendants of this family in the male line. Here's one example:
Hamelin Plantagenet, 5th Comte de Warren had William, 6th Comte de Warren et Surrey who had Jean, 7th Comte de Warren et Surrey who had a younger son Sir Edouard de Warren who removed to Ireland and had a son Nicholas Warrren, Esq. who had a son William Warren, Esq. who, in exchange for one of his English domains received Corduff Castle which remained in the family until the 19th c. Upon the death of the 8th Earl in England the Earldom of Surrey passed into the Arundel family while the Norman title, Comte de Warren passed de jure to William of Corduff, Co. Dublin. He had Edward Warren Esq. of Corduff Castle who had Richard Warren, Esq. of Corduff Castle who had Edward Warren, Esq. of Corduff Castle who had John Warren, Esq. of Corduff Castle who had Nicholas Warren, Esq. of Corduff and Seatown who had Thomas Warren, Esq. of Corduff and Clonestorke who had Nicholas Warren, Esq. of Corduff, Swords and Sillock had Edward Warren of Corduff, Swords, Sillock and Seatown, Gent. who was a Jacobite and who after the Boyne removed to France as did many of the Irish nobility and entered into the service of the Duke of Lorraine and in recognition of his direct descent from the earls of Warren was given letters patent as Comte Edouard de Warren and had Francois Joseph Patrice, comte de Warren who had Jean Baptist, comte de Warren who had Edouard Francois Patrice, comte de Warren who had Lucien Adolphe Esprit, comte de Warren who had Edouard Francois Patrice, comte de Warren who had Marc Marie Edouard, comte de Warren who had William Marie Georges Edouard Emmanuel, the present comte de Warren of chateau de et a Fontaine de Chaalis b. 1936 his son Count Laurent Marie Francois de Warren will succeed him as head of the this ancient House.
Although Warrens in name and title they, apparently, have pure Plantagenet blood in the male line, and are in direct descent from the ancient French Counts of Anjou.