[mensetmanusman]

Visibly transparent effective IR blockers are quite expensive due to the optics involved.

[bradknowles]

Thing is, the dark tint isn't that great at blocking IR. It's blocking more visible light than IR.

So, yeah -- the stuff that actually blocks IR is more expensive. But if you really want to block IR, then that's what you should be getting.

Otherwise, if you're getting the dark tint, then you should be honest with yourself about what it is that you're primarily blocking.