Expect 30 thru 50 Euro per loco, 10 thru 20 Euro per car (maybe more if you have the original packaging).
If you want to sell on ebay you should find out the Märklin (and/or Koll) reference numbers of the items.

The streamlined steamer looks pretty old - could be worth more than the others.

Welcome to the forum. It's a bit hard to get a handle on what condition these item are in as you seem to have take the pictures with an orange filter on your camera, which tends to make it hard to see the detail.

I would guess that most of the coaches would be around $30 - $40 US, the Rheingold perhaps a bit more. Most of the locos maybe around $80 - $100 US. The freight cars around $20 - $30 US.

This of course is dependant on condition, the blue E10 looks a bit scuffed. The SK800 is worth more possibly. Krokhunter (a forum member) should be able to give you an idea on this one.

The transformers are worth around $20 - $30 US.

The drawings are probably worth nothing.

P.S. It would be good if you could put your country of origin in your profile. Cheers.

You have a second chance to involved to a great hobby.Do not sell
them.It is so simple.

Ebay is probably the best place to sell these items.

Your best bet is Ebay, you will get the most for it as the bidders set the price. Set up a Pay-Pal account (yes, I know it causes ozone holes and snatches young children away in the night but I've had no problem with it) for a faster sale. Good descriptions and better pictures mean great final prices. If you go that route, feel free to contact me and I'll be more than happy to walk you through it.

Hello gchang 817,
You didn't state that these were Marklin items but obviously all are not. Pics 3,5,10,11,13,18,19,21,23,27,30,32,and 33 show a lot of items I haven't seen before despite the relex couplings. Are they Electrotren, Liliput, or other makes? That would help as well in determining the prices. Marklin items typically sell for a higher premium than the other makes but not always true of course depending on rarity and condition. If it were possible to at least list your items by make instead of making the mistake some folks make in listing their HO items as "Marklin" when they are not will save some grief in non sales, unintended seller's deception, and just not targeting the right bidders. You have some nice items in need of a little TLC to be right.

It takes a bit of research to find out what everything is worth unfortunately. A dealer selling in Marklin may not necessarily be able to help you any more than the generic replies so far if he only sells new items. It really takes a little time on your part to see first what you actually have on hand and then what it's worth in the condition offered. Most of the items should have a manufacture's name under the frame. Since you probably don't have the boxes(I assume), you can search Ebay for say, Marklin gondola or diesel locomotive, Liliput blue passenger car or just Liliput passenger in current auctions or completed auctions. I'm only being basic here in case you aren't familiar already. You might just find the exact item number and what that car in it's condition lists or sells for. Many Marklin items actually have quite a few variations over the many years of manufacture and that matters a lot to folks like me who collect just for the differences. You could always cast caution to the wind and list your items such as Marklin streamlined locomotive. You might do well having the market determine value. Just be sure of the category to get the best exposure. A dealer will certainly want to give you pennies on the dollar and then do this very thing himself. If you lived near me I'd post it all for you. It's seems difficult at times when you seek help and get little in return but there are just so many variables to consider.