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 $37, a growth of 235%.
Most valuable 2003 LEGO Seasonal set
10090 Turkey $11.98
Highest growth 2003 Seasonal set
10080 Angel +335.34%
4 sets

10071 Mr. Bunny

Theme / Subtheme Seasonal / Easter
Year 2003
Pieces 25
Availability Retired
10071 LEGO Easter Mr. Bunny
Retail $2.49
Value $7.01
Growth  +181.5%
Annual growth 8.4%

10079 Snowman

Theme / Subtheme Seasonal / Christmas
Year 2003
Pieces 42
Availability Retired
10079 LEGO Christmas Snowman
Retail $2.49
Value $6.90
Growth  +177.1%
Annual growth 6.3%

10080 Angel

Theme / Subtheme Seasonal / Christmas
Year 2003
Pieces 33
Availability Retired
10080 LEGO Christmas Angel
Retail $2.49
Value $10.84
Growth  +335.3%
Annual growth 3.8%

10090 Turkey

Theme / Subtheme Seasonal / Thanksgiving
Year 2003
Pieces 54
Availability Retired
10090 LEGO Thanksgiving Turkey
Retail $3.49
Value $11.98
Growth  +243.3%
Annual growth 5.7%