In 1979, LEGO released 7 Technic Supplementary sets, all of these sets have been retired. For that year, the total price of all retail sets cost $47, today those sets are valued around $360, a growth of 659%.
Most valuable 1979 LEGO Technic Supplementary set
879 Gear Wheels with Chain Links $111.41
Highest growth 1979 Technic Supplementary set
877 Steering Gear Parts +2971.14%
Most owned 1979 Technic Supplementary set
880 12 Volt Motor
7 sets

874 Yellow Beams with Connector Pegs

Theme / Subtheme Technic / Supplementary
Year 1979
Pieces 38
Availability Retired
874 LEGO Technic Yellow Beams with Connector Pegs
Retail $5.00
Value $27.64
Growth  +452.8%
Annual growth 3.7%

875 Red Beams with Connector Pegs

Theme / Subtheme Technic / Supplementary
Year 1979
Pieces 38
Availability Retired
875 LEGO Technic Red Beams with Connector Pegs
Retail $5.00
Value $20.63
Growth  +312.6%
Annual growth 5.0%

876 Blue Beams with Connector Pegs

Theme / Subtheme Technic / Supplementary
Year 1979
Pieces 38
Availability Retired
876 LEGO Technic Blue Beams with Connector Pegs
Retail $5.00
Value $19.97
Growth  +299.4%
Annual growth 3.0%

877 Steering Gear Parts

Theme / Subtheme Technic / Supplementary
Year 1979
Pieces 24
Availability Retired
877 LEGO Technic Steering Gear Parts
Retail $3.50
Value $107.49
Growth  +2971.1%
Annual growth 7.6%

878 Piston Parts

Theme / Subtheme Technic / Supplementary
Year 1979
Pieces 52
Availability Retired
878 LEGO Technic Piston Parts
Retail $4.50
Value $33.19
Growth  +637.6%
Annual growth 4.3%

879 Gear Wheels with Chain Links

Theme / Subtheme Technic / Supplementary
Year 1979
Pieces 87
Availability Retired
879 LEGO Technic Gear Wheels with Chain Links
Retail $4.50
Value $111.41
Growth  +2375.8%
Annual growth 7.1%

880 12 Volt Motor

Theme / Subtheme Technic / Supplementary
Year 1979
Pieces 22
Availability Retired
880 LEGO Technic 12 Volt Motor
Retail $19.99
Value $39.99
Growth  +100.1%
Annual growth 5.3%