Depends where you get them from & what you get. A set of 4.5 D-Jet heads out of a junkyard car, have a shop do the seats & valve stems & seals on both for peace of mind, shouldn't be more than $1k with the job (and probably $200 if you just get heads that "Look good" and pop them on).

__________________
Current:
2021 Charger Scat Pack Widebody "Sinabee"
2018 Durango R/T

Previous:
1972 280SE 4.5
2014 Jeep Grand Cherokee Limited "Hefe", 1992 Jeep Cherokee Laredo "Jeepy", 2006 Charger R/T "Hemi"
1999 Chrysler 300M - RIP @ 221k