As an FYI, I just got a quote for replacement boots from Goodrich including installation for $14 k on my 1977 FT337GP.
It was suggested that Aviall, AAR and API would also quote and give good pricing for boots only, $10 k +/- was suggested.
My A&P has said that with four of you helping, each having six hands, installation is a breeze and the most fun you have had in a long while.
Dave - N456TL