so i can tell you you're definitely wrong on s. astral, they were up to about 27m/stack prior to sparks nerf. i can't say for certain on heroism but if you go through my posts i wrote down prices at the time. you can always check waybackmachine to find your own numbers as well.
sparks nerf was June (https://forum.square-enix.com/ffxi/threads/56924-June-10-2020-%28JST%29-Version-Update)
June (2020):
Riftcinder - 800k/1 (160)
Riftdross - 400K/1 (94)
Pluton - 300k/99 (172)
Beitetsu - 920k/99 (73)
Riftborn Boulder - 700k/99 (183)
Heavy Metal Plates - 7,900k/99 (80)
High Purity Bayld - 780k/99 (97)
Alexandrite - 820k/99 (167)
M. Silver - 375k/1 (103)
L. Jadeshell - 400k/1 (99)
100 Byne Bill - 370k/1 (83)
S. Astral Detritus - 27,000k/99 (111)
so these prices start 5 months after the nerf
November (2020):
Riftcinder - 550k/1 (154)
Riftdross - 300K/1 (94)
Pluton - 180k/99 (76)
Beitetsu - 650k/99 (90)
Riftborn Boulder - 300k/99 (112)
Heavy Metal Plates - 5,900k/99 (144)
High Purity Bayld - 460k/99 (193)
Alexandrite - 400k/99 (280)
M. Silver - 220k/1 (102)
L. Jadeshell - 210k/1 (63)
100 Byne Bill - 200k/1 (29)
S. Astral Detritus - 15,700k/99 (37)
Rostam - 96,000k (4)
Comm. Charm +2 - 49,000k (6)
Beastmen's Medal - 1,500k (145)
Kindred's Medal - 1,800k (101)
Demon's Medal - 1,400k (79)
February (2021):
Riftcinder - 650k/1 (51)
Riftdross - 400K/1 (195)
Pluton - 160k/99 (51)
Beitetsu - 650k/99 (33)
Riftborn Boulder - 145k/99 (147)
Heavy Metal Plates - 5,200k/99 (60)
High Purity Bayld - 700k/99 (11)
Alexandrite - 300k/99 (105)
M. Silver - 140k/1 (82)
L. Jadeshell - 171k/1 (39)
100 Byne Bill - 200k/1 (2)
S. Astral Detritus - 14,800k/99 (72)
Rostam - 80,000k - (6)
Comm. Charm +2 - 43,800k (4)
Beastmen's Medal - 900k (191)
Kindred's Medal - 1,300k (179)
Demon's Medal - 1,100k (31)
https://web.archive.org/web/20200512020917/https://www.ffxiah.com/
s. astrals appear to be 280k/single from the feb 2020 snapshot, can't see the stack price. anyways.. things have definitely went down in value as gil price has went up.
last edit, found my post of june