I just got a pair of PK2s this afternoon from a local that organized a bulk. Only cost me about $57 (converted), and although I have customs on the way, I figured I'd have nothing to lose and I wanted to try these out for myself and see if all the favorable reviews were actually true. So much accolade for these buds have certainly injected curiosity within me.
I originally wanted the PK1 so I didn't have to upgrade anymore when earbuds were concerned, but the seller said PK1 wasn't exactly popular over here (I'd imagine so, most probably because of its price) and he wasn't bringing in any, so I opted for the PK2 instead.
I must say, these hardly sound like earbuds. I own the stock Apple earbuds that came with my iPod and a pair of Sennheiser MX160s that I picked up for like $15, and those were just disappointing. After those, I was convinced it was either headphones or just IEMs, no more earbuds.
The PK2s changed my opinion. These sound like headphones, not earbuds. I was told they would need about 100 hours of burn-in time before they'd sound good, but they're already decent as-is. There's room for improvement, so I'm still hopeful.
These sound superb out of my iPod without an amp. I don't exactly own any high-end amplifier anyway, just a cMoyBB.
I've got to say, I'm very satisfied. Although my UM3X is superior, it's simply not ideal during situations like driving. Wearing those are a hassle as well, as I have to compress the foam before inserting them into my canals. And having read about the excellent build quality (who would have thought; being built in China and looking like $1 stuff?!), I'll be wearing these to sleep every night.

I won't have to worry about crushing it or damaging it; and even if I do it on accident, I'd gladly fork out for another pair.
I love how these earphones look, too. Cheap facade: but such impressive sound.
Anyway, I'm now thinking of getting the PK1, as per my original intent. However, I'm just wondering: is it worth it? Is it worth the extra money shelled out? I know there's an improvement, but is it very distinct and pronounced? Is it an improvement that justifies the price tag? If the improvement is just subtle and not a huge leap, I'll probably be happy enough with the PK2.