The gas struts on the hatch of my topper are shot - they won't hold it up any more. Where's the best place to get replacements? Does Crappy Tire have this kind of thing?

 

Yes but there not cheap $25+ each....
Try your luck at a wreckers or take a piece of 1/2 plastic pipe of the same length as the exposed strut shaft when the hatch is opened, cut a 1/4 slot along it's length and drill a small hole in one end so that you can tether it to the strut.
Lift the hatch , snap the plastic pipe in place and viola ! no more bumps on the head.
OF course you need two hands to do this so you have to put down whatever your carrying but it's better than clamping a pair of vicegrips on the shaft and will work until you can find replacement struts.

Frank