From the Piston thread:
I don't see a point in debating simply because of the various factors that can affect the way each person ranks their gear.
Apologies first that I don't know all the audiophile lingo but here's my personal take:
I prefer Pistons over my VSD1 because I found it had better clarity in the mids and highs. The clarity was comparable to my Monster Gratitude. However Gratitude had harsh highs and Pistons did not.
As for lows, I like to have bass when the song calls for it. Does that make me a basshead? I'm not really sure. I found Piston's bass had more depth than the other two, but lacked the punch/tightness. But all changed after I pulled out the foam from the nozzle. I'm still in the process of burn-in (16 hours and counting) but to me after the mod the Pistons have already surpassed both VSD1 and Gratitude as my go-to iem's.
I will probably give the Grats to my wife, and keep the VSD1 for going out/exercise. I don't really see Pistons as being practical for running around.
For iem's, the most I've ever spent was the $60 for Gratitude on Amazon, which was a price I was pretty happy with considering the original price was $220. But with Pistons being just $25, I'm not sure (without increasing my budget significantly) I'll be able to find better value.
As for budget -- my wife and I have this agreement that applies both ways: Anything under $50 I can get no questions asked. $50-100, I have to let her know. $100+ she has veto power.
You can get them from here: http://www.ibuygou.com/p-original_xiaomi_piston_earphone_updated_version_brown-5708-usd.html