I’ve been looking for one myself. Found one. Dragged my feet and missed the opportunity. I’ve found another…but no idea of the quality. https://www.amazon.com/Rhode-Island-Novelty-Elrocla-Rocket/dp/B00CH88816/ref=dp_prsubs_1?pd_rd_i=B00CH88816&psc=1

There is a similar one for $32 on Amazon. Obviously a cheaper version than the Mathmos but still cool!

18" ROCKET SHIP LAMP https://www.amazon.com/dp/B00CH88816/ref=cm_sw_r_cp_api_i_hGw6Eb0QTDC2X