I am certain Black Note is not longer bottled in 750ml bottles, not sure on the Consecration but I don't believe so (recently stopped IIRC). As far as price.... I contribute nothing.
Consecration hasn't been in 750's for quite a while... I believe just the first couple batches. I don't remember the $$$, but both of them are so rare right now cost will likely be a pretty minimal factor.
I guess it's in the eye of the beer holder at some point or which side of the coin you are on (sour or stout lover). It could go either way. I was just looking at the 750ml Consecrations which are ~5+ years old and assuming that could add a little more power behind it. 1:1 wouldn't be far off though. I wouldn't necessarily trade my last '09 Consecration for a BN but maybe that's just me Cheers!
I traded for a 750 Consecration once and it came with a sticker saying it was $29.99, though it may have come from a shop in Philadelphia based on my trade partners location(resulting in a higher price). Black Note was $20 and was only available at the Bells General Store. While there are less Black Note 750s, I don't think they demand much and don't taste as great as they once did(Black Note doesn't age well IMO). I think there were something like 1,500 750's produced during the first run, they may have done two runs of 750's but have only bottled in 12oz as of recent. FWIW, I traded a 750 Black Note for a 2012 Classic Gueuze earlier this year, but I love gueuze so I didn't mind it. The Batch 3 Consecration 750 wasn't that great, I prefer it fresh.
This. Rarity aside those 750 consecrations taste phenomenal. There's a Seattle bottle shop that sells them for on site consumption and they're incredible.