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 $41, a growth of 485%.
Most valuable 2018 LEGO Promotional Minifigure set
5005233 Hamleys Royal Guard $17.66
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 $17.66
Growth  +152.6%
Annual growth 11.2%

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 $10.66
Annual growth 16.5%

5005251 Penguin Winter Hut

Theme / Subtheme Promotional / Minifigure
Year 2018
Pieces / Minifigs 6 / 1
Availability Retired
5005251 LEGO Penguin Winter Hut
promotional
Value $12.55
Annual growth 1.7%