Super.Fi 3 for me. Was a step backwards from the Metro.Fi 170 with sibilant, screeching highs, terrible form factor and fit and the bass was anemic compared to the MF170.
Senn HD205. Lasted maybe a month or two before the cheap, flimsy wire copped out on me and blew out the right side. Because of that I refuse to buy any Senn phones under an HD515. I would also have to count pretty much any Skullcandy product I've ever wasted money on, too. (That was when I was younger and didn't know anything of the audiophile world yet, ahahahaha.)
Denon AH-P372K. Completely different sound to its cousin the 1001. Uncomfortable to wear. A hassle to fold away and store in a bag. Right speaker louder than the left. Didn't bother having it replaced or repaired.
Sony MDR-V300. I didn't know any better. I thought, "Sony! Must be good!"
So, I spent $50 on the precursor to Bose Triport fart cannons.
Since then, no regrets about any audio-related purchases.
I was happy with the first pair... then got an iPhone and needed a newer pair that was compatible with the recessed headphone jack (gave away first pair). I was happy with the second pair until my nephew thought it a grand idea to tie them to his door as a means of locking it.
bought 2nd and 3rd pair at the same time (anticipating one of them being destroyed). These were not the same build quality as my first two pairs (different wires which lost connection to the mini-plug within a month each).
The university I (soon to be graduating from) had them on sale at the end of the year so I bought a 5th and 6th pair. I made sure to be extra careful with them... one broke, one still works. (Well technically, now they all work since I joined this site and realized I could simply fix them)
The primary reason I kept purchasing the ink'd buds was because the rubber tips fit my ears perfectly.
But now I have a pair of wooden altecs fitted with some leftover ink'd rubber tips that I use as my primary IEM's, and a pair of JVC-HA700s that I use as my primary 'phones
I regretted buying the Grado SR80's. I thought they sounded decent but didn't have the build quality or comfort befitting of a $100 headphone and I soon sold it.
Oddly, I kind of regret selling it at the same time...