In 2018, LEGO released 3 Harry Potter Promotional sets, all of these sets have been retired. For that year, the total price of all retail sets cost $8, today those sets are valued around $118, a growth of 1377%.
Most valuable 2018 LEGO Harry Potter Promotional set
40289 Diagon Alley $60.00
Highest growth 2018 Harry Potter Promotional set
5005254 Harry Potter Minifigure Collection +335.92%
3 sets

40289 Diagon Alley

Theme / Subtheme Harry Potter / Promotional
Year 2018
Pieces / Minifigs 374 / 1
Availability Retired
40289 LEGO Harry Potter Diagon Alley
promotional
Value $60.00
Annual growth 17.1%

5005254 Harry Potter Minifigure Collection

Theme / Subtheme Harry Potter / Promotional
Year 2018
Pieces / Minifigs 25 / 4
Availability Retired
5005254 LEGO Harry Potter Minifigure Collection
Retail $7.99
Value $34.83
Growth  +335.9%
Annual growth 12.2%

6385434 Golden Snitch

Theme / Subtheme Harry Potter / Promotional
Year 2018
Pieces 35
Availability Retired
6385434 LEGO Harry Potter Golden Snitch
promotional
Value $23.19
Annual growth 7.6%