In 1990, LEGO released 2 Promotional sets across 2 subthemes, all of these sets have been retired. Subthemes for that year included Ferries and Value Packs. For that year, the total price of all retail sets cost $10, today those sets are valued around $2,389, a growth of 23816%.
Most valuable 1990 LEGO Promotional set
1998 Silja Line Ferry $1,274.10
Most owned 1990 Promotional set
1675 Three Set Bonus Pack
2 sets

1675 Three Set Bonus Pack

Theme / Subtheme Promotional / Value Packs
Year 1990
Pieces 165
Availability Retired
1675 LEGO Three Set Bonus Pack
Retail $9.99
Value $1,115.12
Growth  +11062.4%
Annual growth 8.6%

1998 Silja Line Ferry

Theme / Subtheme Promotional / Ferries
Year 1990
Pieces 370
Availability Retired
1998 LEGO Silja Line Ferry
promotional
Value $1,274.10
Annual growth 5.9%