In 2003, LEGO released 4 Seasonal sets across 3 subthemes, all of these sets have been retired. Subthemes for that year included Christmas, Easter, and Thanksgiving. For that year, the total price of all retail sets cost $11, today those sets are valued around $42, a growth of 283%.
Most valuable 2003 LEGO Seasonal set
10090 Turkey $17.36
4 sets

10071 Mr. Bunny

Theme / Subtheme Seasonal / Easter
Year 2003
Pieces 25
Availability Retired
10071 LEGO Easter Mr. Bunny
Retail $2.49
Value $6.99
Growth  +180.7%
Annual growth 8.9%

10079 Snowman

Theme / Subtheme Seasonal / Christmas
Year 2003
Pieces 42
Availability Retired
10079 LEGO Christmas Snowman
Retail $2.49
Value $6.96
Growth  +179.5%
Annual growth 6.4%

10080 Angel

Theme / Subtheme Seasonal / Christmas
Year 2003
Pieces 33
Availability Retired
10080 LEGO Christmas Angel
Retail $2.49
Value $10.70
Growth  +329.7%
Annual growth 3.9%

10090 Turkey

Theme / Subtheme Seasonal / Thanksgiving
Year 2003
Pieces 54
Availability Retired
10090 LEGO Thanksgiving Turkey
Retail $3.49
Value $17.36
Growth  +397.4%
Annual growth 6.1%