葫芦 (húlú) are dried gourds, which are then engraved, often in very minute detail. They range in price from a few kuai to hundreds and thousands. You can find them in the local specialities shops, if you walk west from the Lanzhou Hotel, along Dōnggăng Xī Lù (东岗西路), west of Tiānshuì Lù crossing (天水路口往西走). There is also a well-known shop at the top of the White Hill Pagoda. The photos below were taken at Huáng Miào.