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 $366, a growth of 670%.
Most valuable 1979 LEGO Technic Supplementary set
879 Gear Wheels with Chain Links $113.33
Highest growth 1979 Technic Supplementary set
877 Steering Gear Parts +3027.71%
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 $28.13
Growth  +462.6%
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 $21.49
Growth  +329.8%
Annual growth 5.3%

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 $19.87
Growth  +297.4%
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 $109.47
Growth  +3027.7%
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 $33.47
Growth  +643.8%
Annual growth 4.4%

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 $113.33
Growth  +2418.4%
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 5.4%