Amazon has Southwire Romex 12/3 Indoor Electrical Wire: 100′ SIMpull $34.60, 50′ SIMpull on sale for $17.45. Thank you Mike for posting.
Notes from Amazon:
Coated in patented SIMpull Cable Jacket for easier pulling, stripping, and installation
Primarily used in residential wiring as branch circuits for outlets, switches, and other loads
UL Listed type NM-B
12 gauge, 3 conductors with ground, 50′ per coil
Made in America