What are you wanting to do with your computer? If you 'looooove' your MacBook and store your entire life upon it (as one is wont to do on a primary computer), you may find the Air is simply not for you. Not enough storage might be an issue for you.
I have an 11" Air and when I considered it, I was worried about the storage on it. We get so used to computers with GBs worth of storage, that we don't think how we use the space. Kinda like filling a basement with stuff when, really, a walk-in closet will do. Anyway, I did the math of the stuff I wanted to hand daily and in a portable kinda way and realized I could easily fit it on a 128 MB Air. The less-important stuff I shunted over to a partition on a portable HDD which also has a partition for the Time Machine backups. In a pinch, I could take this drive with me when I travel, but frankly, I haven't had the need.
The other issue when moving from a MacBook is the Air's lack of a optical drive - and again, I had to think how I really use my computer. "When was the last time I used a CD/DVD on my computer?" In reality, quite some time ago. And while I admit I have an external optical drive from another time/project, again, I can't tell you the last time I used it.
The upshot is, are willing on 'sacrificing' stuff for more lightweight portability? Are you willing on doing a purge if necessary, or do you really just want to recreate your environment on another capable computer? If it's the latter, and you 'looooove' MacBooks, get another MacBook.
As noted above, the Apple Store's Refurb section is a good place to start for an Air (or MacBook) - and all product there comes with a full warranty - and, dare I say it, possibly a better testing process than 'new factory'. Or check out your favorite Big Box - they may have 'old' (last model) product in a back room that they still need to get rid of. That's how I got mine - brand new, but a couple of weeks after an Air refresh. Sold it to me (with both the regular Apple as well as an additional year in-store extended warranty) for 15% less than the new model.