I got my Piston 2.1's from ibuygou. Took 3 weeks to get here and just bought another pair (couldn't pass them up for $16).   The sound quality is very good, especially after the mod where you remove the foam from under the grill. I would highly recommend this pair -- comparable to most...

http://www.ebay.com/itm/Sony-MDRXB50AP-Extra-Bass-Earbud-Headset-Black-Open-Box-1-each-/251754387850?pt=LH_DefaultDomain_0&hash=item3a9dbb198a

These are ridiculously bassy but still have fairly good SQ otherwise: http://www.amazon.com/Sony-MDRXB50AP-Extra-Earbud-Headset/dp/B00JRD13T8/ref=sr_1_1?ie=UTF8&qid=1422650761&sr=8-1&keywords=sony+mdrxb50ap   They go down to 4 Hz and you really, really, really feel it.   Can also get open...

I have a pair of Sony MDR XB50AP and they have so much bass (probably 50% more than the Sennheiser CX 300 II's). When I first used them, the bass was uncomfortably strong. With their huge drivers, you really feel the bass inside your head.    The sound quality on them is pretty good -- similar...