In 1959, LEGO released 6 System i Leg Supplemental sets, all of these sets have been retired. For that year, the total price of all retail sets cost $3, today those sets are valued around $432, a growth of 14303%.
Most valuable 1959 LEGO System i Leg Supplemental set
280 Red Sloping Roof Bricks $101.34
Largest 1959 LEGO System i Leg Supplemental set
282 2x2 Sloping Roof Bricks Red 22 pieces
6 sets

280 Red Sloping Roof Bricks

Theme / Subtheme System i Leg / Supplemental
Year 1959
Pieces 14
Availability Retired
280 LEGO Red Sloping Roof Bricks
Retail $0.50
Value $101.34
Growth  +20168.0%
Annual growth 7.1%

280-2 Blue Sloping Roof Bricks

Theme / Subtheme System i Leg / Supplemental
Year 1959
Pieces 14
Availability Retired
280-2 LEGO Blue Sloping Roof Bricks
Retail $0.50
Value $36.75
Growth  +7250.0%
Annual growth 5.5%

281 1x2 and 3x2 Red Sloping Bricks

Theme / Subtheme System i Leg / Supplemental
Year 1959
Pieces 21
Availability Retired
281 LEGO 1x2 and 3x2 Red Sloping Bricks
Retail $0.50
Value $40.42
Growth  +7984.0%
Annual growth 5.7%

281-2 1x2 and 3x2 Blue Sloping Bricks

Theme / Subtheme System i Leg / Supplemental
Year 1959
Pieces 21
Availability Retired
281-2 LEGO 1x2 and 3x2 Blue Sloping Bricks
Retail $0.50
Value $99.62
Growth  +19824.0%
Annual growth 7.1%

282 2x2 Sloping Roof Bricks Red

Theme / Subtheme System i Leg / Supplemental
Year 1959
Pieces 22
Availability Retired
282 LEGO 2x2 Sloping Roof Bricks Red
Retail $0.50
Value $53.19
Growth  +10538.0%
Annual growth 6.1%

282-2 2x2 Blue Sloping Roof Bricks

Theme / Subtheme System i Leg / Supplemental
Year 1959
Pieces 21
Availability Retired
282-2 LEGO 2x2 Blue Sloping Roof Bricks
Retail $0.50
Value $100.76
Growth  +20052.0%
Annual growth 7.1%