I had originally gotten the flip key (ESI, if memory serves) from Korean Auto and it was definitely a quality unit, but rather expensive. The price had come down a bit, but not enough to justify purchasing a second one, although I wanted it to consolidate my keyless fob and key to make it easier to find/lose/share/etc.
I then ordered one of the units from e-bay which looks almost identical, and while it is respectable, it certainly has a cheaper feel. My ESI fob is closer in materials and movement to my friends VW fobs, where the Chinese one is lighter and as previously mentioned, the key part is a snug fit, length-wise.
I will say that one benefit of the e-bay key is that the Panic button on the back is slightly recessed. On the ESI fob, the key ring is perfectly positioned to swivel back and lightly touch the panic button when in a pocket and bending over. My neighbors have gotten used to it. Not good for an alarm, I guess! "Wolf!...Wolf!...Wolf!"