LEGO 2312 Supplementary Bricks is a vintage Duplo set from 1987 valued at $102 for new and sealed sets, up 535% from an original retail price of $15.99. Annual appreciation has averaged 6.14% since release. Used copies are valued between $28 and $35 depending on condition.
LEGO 2312-1 Supplementary Bricks is a Duplo Supplementary set released in 1987, containing 39 pieces. It provides an assortment of basic DUPLO elements in red, blue, yellow, and green, including 2x2, 2x4, and 2x8 bricks. Notable inclusions are the 2x4x2 rounded-end bricks and a yellow 2x6x2 inverted double arch. It was a pre-school set.
A new and sealed Supplementary Bricks is currently valued at around $102, with annual growth of approximately 6%, which is higher than other Supplementary sets. The average used price is $29 for those in good overall condition. Based on current trends, this set could be valued near $107 within the next year. New and sealed listings currently range from $90 to $173.