fit comfortably onto an airline tray

Not too long ago, a budget laptop was, by default, a big, ugly plastic box. It may have gotten the job done in terms of school or office work, but it wasn't going to turn any heads at the coffee shop, or fit comfortably onto an airline tray (with the exception of too-small Netbooks, which had their own list of problems).
We'll look back on 2012 as the first year when budget laptops really got a fair shake, with many models looking and acting much more like their expensive cousins than ever before.
Even at the very low end of budget -- laptops that are $600 or under -- you can get a slick-looking HP Envy Sleekbook, or a powerful Acer Aspire V5.
Here are a handful of recent favorites, from 11-inch ultraportables to 17-inch desktop replacements, each of which costs about half as much as a 13-inch MacBook Air