First of all welcome to the forum Daniel.

I'm not an expert on values of old locomotives,but what I can say is that both of the locos are special and much sought after in auctions and e-bay.
Much of the value is depending on the condition of the loc and whether you have the original box or not.

By the looks of it -excellent photos if I may say so-they're in reasonably good shape.

The CCS800 also known as "Krokodil" has been made form 1947 until aproximately 1959.
I have to compare your pictures with the descriptions in Koll's catalogue to give you an educated guess on the model year.

The SEH800 will make tick the hearts of Dutch railway fans a little faster.
There are several versions made from approximately 1955 until 1966.

I'll try to dig out more information in Koll's and hope someone with more knowledge on the forum will provide info too.

Kind regards
Guus

Guus! It's called a "slider' The Thinghy.
Nice looking engines for the fact that they have been stored in an attic for a long time, a nice addition to a collection. Welcome to the forum Daniel.

True, AFAIK you cannot search online for the prices listed in Kolls Preiskatalog. At least, not for these models, for some more recent ones, you can find the prices listed at Stummi.de (in the Märklin database)

But, please keep in mind that - although very knowledgable - Joachim Koll is not always correct about the prices, they only provide you with some indication of the - potential - value of the model.

Thanks! i might have to get my hands on one of these catalogues then, as i have a couple more boxes of locomotives, cranes, buildings etc. from the early 50's.

On the question of the value of older Märklin, i have gotten the impression that the market is so strong that a listing on ebay.de will generate a fair price, i might be wrong though.

I've cleaned out my attic but found only empty boxes, old receipts, and some suitcases. Your attic is better.

Daniel, to get the "street price" Ebay is generally a better tool than Koll's... Koll lists the items in mint condition with boxes, and you could say that it is the maximum price for an item if it is a perfect sample - even if some sellers claim that the value is that high even for items with visible wear.

So, search Ebay for auctions on the items - both Ebay.com and Ebay.de - and look at the prices for finished auctions. Sometimes they can be even higher than Koll's, and that gives an idea about how desirable the items really are...

Taking a middling price
I guess
ccs 800 $600
Seh800 $300
regards