Across the board I'd pay a little more than what Eric has listed, but not a lot more. What he's listed is what I might have looked for 10 years ago, but prices have gone up - especially during COVID - so I've adjusted my expectations a little higher. At least from online retailers... if this is a private purchase then yes what Eric has listed is more reasonable.
1996 Vesuvio is an excellent Port. Like Eric my favorites from that time frame are usually 1994, 1997, and 1992, but when we did a small vertical of 1994 - 1998 I ranked the 1996 in the middle at 94 points. (Top to bottom, 1994, 1995, 1996, 1997, 1998. Totally a coincidence that it was in date order.) Note that when I rate Ports at tastings I'm rating them based on how much I
like them, not how good of a Port that I think they are. I think the 1997 is in some way a higher quality Port than the 1996, but on that night I
liked the 1996 better.
1977 Warre can be a real ringer for me. I don't normally like Warre's Vintage Ports, but the 1977 always surprises me. Good bottles are wonderful. But as Eric said, once you get to 45 years old you start seeing significant bottle variation in any Port, so you just can't be sure. My expectation for this Port would be 92-93 points, but I've had slightly better and slightly worse. I've actually been looking at those bottles on Winebid.com but haven't pulled the trigger yet... but it's tempting!
1985 Dow is, at least for me, in the top echelon of that vintage. The Graham and Fonseca are pretty clearly better for my palate, but the Dow is right behind them. I'd say there's very little risk in buying this bottle provided the provenance is sound.
1994 Cockburn is a Port with which I have limited experience, but what experience I do have says it's a bit disappointing for that vintage. That said, 1994 as a whole is fantastic so even a somewhat disappointing VP from that year can still be very good. I just wouldn't call it excellent, and it just can't really compete with its peers.
2000 Infantado is one of the better Infantados as I recall, but I generally don't like Infantado so I would not personally be interested in this bottle. Their 1992 is excellent, but I think that's their only Port that I would say that about and most are merely good.
And now that I've written that, I just realized that they're probably listed in the order that I would rank them top to bottom.