In 2005, LEGO released 3 Factory sets, all of these sets have been retired. For that year, the total price of all retail sets cost $240, today those sets are valued around $911, a growth of 280%.
Most valuable 2005 LEGO Factory set
5526 Skyline $706.91
Theme Factory
Year 2005
Pieces 607
Availability Retired
5524 LEGO Factory Airport
Retail $39.99
Value $89.78
Growth  +124.5%
Annual growth 3.9%
Theme Factory
Year 2005
Pieces 1,344
Availability Retired
5525 LEGO Factory Amusement Park
Retail $69.99
Value $114.13
Growth  +63.1%
Annual growth 3.2%
Theme Factory
Year 2005
Pieces 2,747
Availability Retired
5526 LEGO Factory Skyline
Retail $129.99
Value $706.91
Growth  +443.8%
Annual growth 5.3%