So, for me, this was perfect.  I love what I got.  
My situation: I actually did not have any steam model stuff, so I didn't have to worry about duplicates.  I was ready to take a little risk and I figured that all I really wanted was at least one item that would be interesting (out of a couple surprises as I decided to go big or go home...)  In truth I like everything I got, but again, I had nothing to start with so a surprise box was interesting to me.   Did they send me stuff of the same value I paid?  In my case, definitely, but given this is the first review, I might be the only person who has ever gone for the surprise box.
I would take the risk again, except now I have some cool items and I think the risk of duplicates has gone up.  I am going to use these items to figure out what my next purchase will be!  I am not going to give a picture, because I fear it will spoil the surprise.  Yes, I did get a steam engine to play with, but I also ordered the big box.  I was hoping if I ordered 4 items, at least one of the random items would be an engine of some type.  Not disappointed. 
...and it arrived on father's day.  I know it is coincidence, but nice cherry on top.