I consider the opportunity cost of a point around half a cent, as that's give or take the gift card rate, which I can substitute for real money at woolworths etc - so the opportunity cost of a 50k business class ticket is give or take $250 plus the $100 or so in taxes.
I try to avoid valuing points because I think it creates spurious accuracy.
But, I believe a point costs a bank or supermarket about 1 cent (I have heard 1.1 cents) per point. If it is redeemed for goods then the going rate seems to be about 0.5 cents per point.
When I acquire points the price I pay can vary from the full 1 cent per point (when I redeem Woolworths points for Qantas points instead of cash back), through 0.4 cents per point (the most expensive credit cards at 100,000 points from a $395 fee), to 0.04 cents per point (70,000 points for a $30 fee for a Commbank card).
When I redeem, I usually do it for premium cabin flights and get a minimum of 2 cents per point - usually a lot more. But it is difficult to really calculate this because you do some things on a OWA that you would never do when paying revenue fares. Last year I came back from Tehran with stops in Tunis and Amman which would never have happened on a revenue fare. I routed hope from Amman via London, Helsinki/Helsingfors and Delhi which was simply nuts. Do I value this at the cost I would have paid on half a (Y) return from MEL-IKA, or do I value it as a revenue (J) DONE fare, or do I price it as separate J revenue flights?
Or on point to point, I am using Velocity points for a 1.15 hour business class flight on Etihad from AUH-MCT. The revenue cost for this is something like $1,300 but if I were paying revenue I would be going Wizzair for $70. I paid more on fees/taxes for my award flight than I would have paid on a revenue flight.
Overthinking value leads to madness. I view points just as a currency (yes!) that allows me to do things I would not otherwise be able to do . For me, that is priceless.