It is worthwhile to compare this sale against Amazon. Barnes and Noble up-prices, and then put it on sale 50% off. For example I found 400 Blows Criterion at the same price on Amazon, and this is a regular price, so there is no reason to rush buying during BN sale.
I find Amazon's regular Criterion prices are nowhere NEAR 50% off of Criterion's own prices. Normaly, you can't buy a blu ray Criterion release for $19.99 through Amazon.com.