I don't know about Spyglass. I paid about $590 for a round down the street, factoring in caddie and everything. The cost didn't color my experience. I did it on a work trip so that $590 was my total out-of-pocket cost to play arguably the best public course in the country, including travel, lodging, and food. From that perspective, it was really a pretty good deal.
How much would I pay? If I got a call from an Augusta member tomorrow offering me a round for, say, $1000, I'd think about it for a long time. I may not be able to justify the cost considering my own budget, but I suspect it's probably worth it.