If you personally don't find restaurant vs. liquor store relevant and will only pay $150 for Dom in any case, then that is clearly a reasonable basis for your personal calculations.
However, I think that in the general discussion of value, the restaurant vs. liquor store distinction is very important.
I'm only saying it's irrelevant in the context of being "captive" in a restaurant because you can't just go out and buy one at retail and bring it in.
i.e. it's two separate things:
1. If something costs $100 retail but $200 in a restaurant, you wouldn't buy it in a different retail store for more than $100; whether you are willing to buy it for $200 in the restaurant is a personal thing.
2. However *if* you are not willing to pay $200 cash for it in a restaurant, you should also not be willing to trade a quantity of another currency you hold that you also value at $200.