Is there a real-time digital viewer for film negatives without scanning each frame?

Yes—there are simple low-cost devices that act more like a camera/webcam with a backlight and negative holder than a true film scanner, giving near real-time preview. Image quality is limited, but they can be good enough for quick review.

Other practical options mentioned:

• Use a camera with a macro lens or slide-copy setup, then view live on a tethered computer or TV.
• Use a phone app such as Positron with a backlight for quick identification.
• For non-digital preview, a light box and magnifier is the simplest option.
• If you want better quality while still reviewing multiple frames efficiently, a flatbed such as an Epson Perfection that scans whole strips at once may be a better workflow than scanning frame by frame.

At your budget, a true dedicated scanner with instant live preview is unlikely. For fast browsing, the best fit is usually a basic digital copier/viewer, a phone-based setup, or a camera + backlight workflow rather than a traditional film scanner.