I less-than three my K145. But that guy selling his K145/S on ebay is on crack if he thinks it's worth 115eu.
Edit: Ahh, I see he's dropped the price to 99 euro. He started out at 150 euro a couple weeks ago. I paid 12 euro for my K145, and i am aware of NOS pairs that can be had for about 80usd.
But yes, it was the supra-aural successor to the K340. The electret is smaller and more efficient, and the construction is far simpler. They use a dynamic driver that is very similar to the K141-style driver used in the K240 and K340 series, but at 400 ohms rather than the 600 ohms in the K141 and K240 or 640 ohms in the K340.
The K145 was among the most ambitious and worst selling products AKG ever released. They are, in fact, still bitter about it.
As I've implied, there are two versions of the K145 - the regular version has a plastic headband with a nylon strap, the /S version has a wire headband with a vinyl strap. They are otherwise identical.
The much rarer K4, which looks like a devious ear incineration device, has a foldable plastic frame, but again the same driver module. The only K4 I've ever seen belongs to head-fi member Tyre.
Now, here's the rub - I like the way my K145 sounds, but was modded by whoever owned it before i did. The earpads are very different from stock, in a way that certainly changes the sound. If you use the search feature, you'll see pics of my K145.