I have been hunting for this coin, but have never seen it at a show. Does anyone know if this coin is ridiculously rare and expensive or if I'm just a bad coin hunter?
Yes, it's ridiculously rare and expensive. You won't find one for sale more often than every few years, and it will be offered by a major auction house. Keep your eyes peeled, and have a suitcase of money at the ready.
The finest one sold by CNG went for $13,000. Click here. But if you were willing to settle for a lower grade, you might pick one up for around five grand.
I agree. The SPES has been a classic rarity for a couple of centuries at least. There was a whole multi-page writeup on the type in the Celator a decade ago or so. I cannot remember all of the specifics, but its a terrifically interesting coin, and terrifically rare, along with well known. All of those things lead to "terrific" prices.
If you're looking for a more affordable Constantinope-only issue with strong religious overtones, I would suggest the Dafne type. Click here.