Zildjian K: between 1984-ish and before 1994 (beginning of laser serial numbers). Somebody else might be able to narrow it down to less than a decade. The things to consider for estimating production era are: it says ZILDJIAN on the bottom rather than just K*, it has lathing with coarse grooves rather than very fine, and it doesn't appear to have a laser stamp. You can see an example of the lathing difference I'm talking about here. The lathing on the one you are considering is more like the example of the Canadian K, and if you scroll down on that link you will see the finer lathing on the 1981-1984(ish) American made Ks.

Paiste 400: 1986-1991. See: http://www.paiste-only.com/paistewiki/index.php?title=400

* yes I know that the K on the bottom replaced the ZILDJIAN later on in the time series and I might have that year (1992? a few years before laser serials) buried somewhere in my notes, but not very handy. I still haven't got back to extend the K coverage of my site. I've been stuck on As for ages. That's why I hope somebody else can provide better evidence for you.

thanks for the info! I appreciate it

When it comes to the Paiste 400s - The 22 "Ride" is a far better cymbal than the 20in Power ride. The 22 is more rare, but way worth it compared to the 20.

thanks for the info. They are selling the k, 400 and some amir hihats. Pretty sure I am going to buy them :)

Got the K and Paiste 400....I was really surprised with the sound of this Paiste ride...great cymbal :)