Green’s Dictionary of Slang

1. (US) $1.

1942		Berrey & Van den Bark Amer. Thes. Sl.
1948		Manone & Vandervoort Trumpet on the Wing 47: The union paid me back the ten buckeroos they had fined me.
1951		J. Reach My Friend Irma II ii: I aint got a million buckeroos there.
1962		J. Viertel To Love and Corrupt 296: Just money. Six or eight million buckeroos. That’s all.
1984		Good Morning America [ABC-TV] They’re racing their way across the country for a million buckeroos [HDAS].

2. see bucker n.³