FYI, I corresponded with the College of Arms recently and the fee for coat of arms research was to be US $700. Still a bit steep, but better than your father's quote.
Additionally, I wonder if you'd be interested in joining the Pierce (and variants) DNA project at FamilyTreeDNA.com. There are no males of the Persse spelling in this large project. It would be great to have your very interesting line represented, and may help you discover earlier roots in England.
My personal interest is that I administer the Bowes (and variants) DNA project, and my subgroup of DNA matches includes two irish Bowe/s lines, an irish Crowley line, and an English Pearse line. The Pearse male doesn't match anyone in the Pierce (and variants) study, and the Persse line isn't in the study, so the possibility is out there they would match each other. My Pearse is from Devon since the early 1600s. Part of the goal of joining for you would be to see if you match the House of Percy, if a current descendent of that line is in the study or can be located to join. Only males with a Pierce variant surname can join because we compare and look for matches between the Y chromosome DNA, since that is passed from father to son with the surname.