Originally Posted by: Shewolf 
Thanks dntowner i have found the engine same set on ebay after your post, for £375.00. The ebay one was immaculate, but only has the one engine, which does help. I now just have to investigate the rest xx
Hi shewolf, welcome to the forum even if possibly only briefly.
As others have pointed out, there are two main considerations;
1: What the exact item/s are - you've listed a couple and this is a good start, the itemised list and some photo's will be a huge help.
2: Condition is everything. The 60's and 70's were in some opinions relatively 'dull' years for Marklin. Sure there were some very collectible models produced during this time, but often these were accidental - ie, a model that was simply not popular at the time (maybe for several years) and was finally withdrawn from the program, and then interest is sparked in it, and everyone wants one because it's rare, not neccessarily because they actually like it - the reason it never sold well in the first place. Sometimes 'collectors' operate in spite of themselves!! (I'm sure I've been guilty of it at times)
Please do be very careful not to get excited by 'ebay prices'. Many of us use Ebay frequently, but you must be guided by actual realised SALES, not what people are asking. Almost weekly we have amusing stories here of outrageous prices being asked for various items which are either not particularly rare, or that are in quite poor condition. As the old anecdote goes in a Tavern that any girl (or guy) looks good after enough alcohol, so too there seems this assumption that if it's Märklin it's valuable, and the condition becomes secondary.
On the other hand, assuming the items you have available are as well-cared for as it sounds, then there is absolutely a good market for them. The most humble of Marklin's items in good condition (and particularly with original box) will get a fair market price, and you can be assured that the advice you receive here will be fair and honest.
Some wonderful trades have been done here in the past similar to your circumstances and the connection you feel to the trains along with knowing they might go to an new appreciative home can be far more satisfying in respect that the item has been chosen for what it is, not what it's worth.
The quoted 3021 is a good example - this loco is available in several variations and which to the untrained eye (no pun intended) would all look identical. It's a nice heavy loco and runs like a dream but are also often found in only average condition. Their solid weight sometimes works against them should they take an unfortunate tumble to the floor, because more damage can result.
Keep us updated, ask as many questions as you like, particularly if you are trying to identify something.
And a tip to help guide us will be to include the printing date code from the box for the item. All Märklin boxes from that era have a printing code and it's always in the same format. For rolling stock it's easy, it will be on one of the end flaps and in the general format like "69565 YN 0267 sh".
This somewhat cryptic code tells us some info about the packaging itself. "YN" can be decoded to the quantity printed (of that particular box or leaflet - NOT the number of items manufactured), the all-important printing date, in this example "0267" means February 1967 and who the actual printer was. The Loco boxes for that era are probably of the 'folded corner' type possibly with polystyrene inserts. The printing code on these can be a little harder to find because you may have to unfold the end to expose it if it's not more visible. They are not usually glued and generally unfold easily, but with care.
Please take these as a guide only because mixups have happened. In your case, if the items were all purchased brand-new from an authorised dealer, then it could be safely assumed that the boxes will match the items and it can help narrow down an approximate production date.
As I say, this is just to help date some of the items.
We're all looking forward to seeing what you have
Regards from Melbourne
Steve