In 1969, LEGO released 2 Universal Building Set Supplemental sets, all of these sets have been retired. For that year, the total price of all retail sets cost $9, today those sets are valued around $349, a growth of 4004%.
Most valuable 1969 Universal Building Set Supplemental set
103 4.5V Motor Set with Rubber Tracks $175.74
Highest growth 1969 Universal Building Set Supplemental set
990-2 Trees and Signs +13745.60%
2 sets

103 4.5V Motor Set with Rubber Tracks

Theme / Subtheme Universal Building Set / Supplemental
Year 1969
Pieces 32
Availability Retired
103 LEGO 4.5V Motor Set with Rubber Tracks
Retail $7.25
Value $175.74
Growth  +2324.0%
Annual growth 5.8%

990-2 Trees and Signs

Theme / Subtheme Universal Building Set / Supplemental
Year 1969
Pieces 13
Availability Retired
990-2 LEGO Trees and Signs
Retail $1.25
Value $173.07
Growth  +13745.6%
Annual growth 5.8%