Disclosure. We're a certified Hans dealer. Not here to sell you anything, just comment on the comments FWIW.
First off, a foam collar in auto racing is good for three things - being uncomfortable, limiting voluntary head movement, and assisting your neck muscles in holding your grape upright in lateral G situations. It is not designed to be a safety device. Read the included literature so carefully crafted by their lawyers.
A Hans is no more likely to impede an emergency egress than any other equipment or apparel involved. It moves with your helmet, neck and shoulders. There is nothing on the Hans to disconnect to get out of the car. Once you pop the harness loose, your Hans is free to go where you go, just as fast as the rest of you.
No piece of safety equipment in your car or on your body is, or represents, a total guarantee that you can't get hurt, burned or chopped into little bits. But just like a multi-layer suit provides additional protection from direct flame, a Hans greatly reduces the risk of neck-injury.
Price? Yes they are expensive and some of the reasons for that has been touched on. Volume, certifications (they cost a lot of $$$, ask Impact!), type of material used, etc.
A Hans can be fitted to any helmet. Easier on a pre-drilled helmet, yes, but older helmets work just as well.
Get the sliding tethers with the quick clips. You'll love yourself for it (please keep those stories to yourself)
Look, no one plans to nose dive into a wall or Armco at a high rate of speed. Your safety is worth what it's worth to you. We take chances in life just rolling out of bed and dodging soccer moms in SUVs. But the stakes can be higher at the track. I don't race without a Hans.
FWIW.