It comes every year, AFAIK in German only.
Band 1 contains locos and sets (train sets, car sets, starter sets), Band 2 contains coaches and freight cars.
There's a bound luxury edition combining Band 1 and Band 2. There is a compact edition without pictures (if you want the prices only).
And there is the special items catalogue for strictly and truely limited editions.

Koll prices are often considered to be too high - but on eBay you often find deals that are even higher than Koll's prices.
Koll checks the prices at auctions and loco swap meetings. There are always chances to get some items cheaper, sometimes someone will pay more.

Edit: not so old goat Tom had to make some corrections (underlined).

Edited by user 29 October 2010 09:59:08(UTC)  | Reason: Not specified

I think this is simply a typo and should read "in German only".

Many people also overlook that Koll's prices refer to crisply new items in their original boxes. Lots of stuff offered on traditional flea markets and eBay is something between "used" and "scrap metal", but nevertheless the sellers ask for Koll prices. Thus the Koll prices are not so unrealistic as it is often claimed in certain web forums.

Otherwise, Koll's catalogs are as reliable as possible. Nobody will ever succeed in compiling a database of Marklin products that is 100 percent complete and without the slightest error.

I think the Koll's Katalog is quite useful to both collectors and traders. The catalog easily identifies the rarer and more desirable items by the price and clearly identifies the differences between versions. The catalogs are produced in the German language, yet with such aids as the translators provided for free by(google and yahoo), one can simply type in the descriptions and get a pretty good translation. One can learn some German along the way too. The pictures are great for identifying differences and nuances. Having a Koll's catalog has greatly increased my enjoyment of collecting Marklin. I have learned so much more than I would have otherwise about the production and scope of the greatest model trains on earth!

Yes, an English edition would be good idea.

Cheers,
Ranjit

2006 same as mine except I have the one minus the photos, and the 2006 version had some of the highest prices, before the economy tanked.

I wish there was something like the Greensburg book now, it had less model numbers but had nice photos and gave good details on why one item was rarer over another.

Is/ was there a Greenburg catalog for Marklin HO? Would a member who is knowledgeable about this topic please write a short piece on Greenburg literature- past or present?
Thanks,
Chas

Yes, it's the full edition as paperback. The Kompaktkatalog comes without photos.
If you only want current prices, then the Kompaktkatalog is the way to go.

Here's the complete range ("ausverkauft" means "sold out"):
http://www.koll-verlag.de/struktur1.html
The complete book and the Spezialkatalog are sold out - new edition announced for April 2011.