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 $468, a growth of 15512%.
Most valuable 1959 LEGO System i Leg Supplemental set
280 Red Sloping Roof Bricks $99.75
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 $99.75
Growth  +19850.0%
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 $79.01
Growth  +15702.0%
Annual growth 6.7%

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 $39.89
Growth  +7878.0%
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 $98.06
Growth  +19512.0%
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 $52.47
Growth  +10394.0%
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 $99.19
Growth  +19738.0%
Annual growth 7.1%