The Shimano road flat bar levers have a flip chip so they can work with any kind of cable brake. There are Claris, Sora, and Tiagra versions but the only obvious difference is the paint. There's one version with a forged aluminum rather than stamped steel lever. You can tell by the ball on the end. A bike shop shouldn't be expected to stock these, as they are a weird conversion part. 99% of bikes with flat bar cable brakes are long-pull. They need all their floor and storage space for bikes and clothes that make them money. Most bike shop work is consumables, adjustments, and bending things back.