The new Mini costs $399, or the same as the 2011 iPad 2. That means you have to choose either a better display or a larger size at that price. Or you can pay $499, or $100 more, for both the decent display and the larger size found in the Air. (For so-so display and a smaller size, you can get the original Mini for $299, down from the $329 when it first came out.)
Of course, there are now plenty of other choices. Microsoft recently refreshed its Surface tablets, which are capable of running Windows programs. Amazon's new full-size Kindle Fire HDX is even lighter than the iPad Air, though it's also slightly smaller, at 8.9 inches rather than 9.7 inches. Samsung has a 10-inch Galaxy Note tablet that comes with a stylus.