There was a time when Hardtop figures were easy to find and generally cheap. But, that changed in the early 2000's as more collectors came online and his popularity started to increase. Now, the figure is coveted and can get fairly pricey. You don't see the figure all that often, but there's some content on him out there. Here's the best on Hardtop from around the web.
Hardtop at JoeDios.com 1
Hardtop at HalftheBattle
Hardtop Pre Production Figure at YoJoe.com
Hardtop at JoeDios.com 2
Hardtop at JoeDios.com 3