Green’s Dictionary of Slang

saw n.1

[abbr. sawbuck n. (1)]

(US) $10.

[US]D. Runyon ‘A Nice Price’ in Runyon on Broadway (1954) 191: And there is my double saw.
[US]A.J. Pollock Und. Speaks.
[US]Goldin et al. DAUL 185/1: Saw. (Abbrev.) See Sawbuck.

In phrases