In 2018, LEGO released 3 Promotional Minifigure sets, all of these sets have been retired. For that year, the total price of all retail sets cost $7, today those sets are valued around $45, a growth of 537%.
Most valuable 2018 LEGO Promotional Minifigure set
5005233 Hamleys Royal Guard $18.83
Largest 2018 LEGO Promotional Minifigure set
5005251 Penguin Winter Hut 6 pieces
3 sets

5005233 Hamleys Royal Guard

Theme / Subtheme Promotional / Minifigure
Year 2018
Pieces / Minifigs 5 / 1
Availability Retired
5005233 LEGO Hamleys Royal Guard
Retail $6.99
Value $18.83
Growth  +169.4%
Annual growth 11.9%

5005250 Party Banana Juice Bar

Theme / Subtheme Promotional / Minifigure
Year 2018
Pieces / Minifigs 5 / 1
Availability Retired
5005250 LEGO Party Banana Juice Bar
promotional
Value $13.17
Annual growth 18.1%

5005251 Penguin Winter Hut

Theme / Subtheme Promotional / Minifigure
Year 2018
Pieces / Minifigs 6 / 1
Availability Retired
5005251 LEGO Penguin Winter Hut
promotional
Value $12.54
Annual growth 1.7%