Ah, good old Smart Boy.
From what I know, this may be the 5th Tetris cartridge. Last two sold for $261 and $214.50. Limbofunk said the following last time:
I talked with the (now retired) owner of the business that distributed theseâ€¦pretty sure they came from a place in South America, but itâ€™s been a few years.
Link ($179.99 BIN) – Little bit worse condition than the rest, but a few dollars cheaper as well.