A very nice Target Roll sold at auction for $1,350 (plus 20% buyer's premium) in March 2019:
https://www.liveauctioneers.com/item/69496584_1957-bally-target-roll-machine
What appears to be the *same* game was resold in November 2019 for $350 (plus 23% buyer's premium). Ouch:
https://www.liveauctioneers.com/item/77039547_1957-bally-target-roll-machine
I'd maybe think about offering $400 for your candidate Target Roll if it matches up well with the photos above, otherwise I'd be adjusting my offer downward.