Seems like a good deal on the E18.
After reading some reviews, however, I walk away not wanting to get it.
Seems like SQ isn't as good as some of FiiO's other offerings.
I don't know if anything has changed since the initial reviews, but I get the impression from the reviews that the E17 sounds better.
But it seems like a good deal for anyone wanting an E18.
Advantages of the E18 over the E17: it works with Android devices, it has a built-in battery for running itself (so it doesn't drain your phone's battery), and it can be used to charge your phone as an external charger in a pinch.
Not sure about SQ since the E17 doesn't even work for my phone so I never even bothered reading comparisons.