The cheap counter-rotating helicopter I got turned out to be a 2-channel piece of garbage. It lifts off, but it's anyone's guess which direction it'll fly in.
I've learned the lesson and now want a proper one.
After careful consideration I've decided to get a last generation Mini Lama.
I can get a new one for €150 (plus 10 for shipping) or a slightly used one for €110 (still don't know whether the price includes shipping).

The seller says the second hand one has been used very sparingly, is undamaged and the battery has only gone through 4 or 5 charge cycles. I've asked him how old the battery is (lithium cells, as you probably know, tend to die in two to three years) and am now waiting for an answer.
He seems a honest guy who knows his stuff and has lots of good feedback (287, 100% positive), so I think I can believe him when he says the heli is in good condition.

Now, consider that:
1) I'm a student without a job and with very little expendable money
2) I've already spent €65 for the abovementioned piece of crap (which I'll hopefully resell soon, but I'll still lose at least some money)
3) I really really don't want another disappointment

Assuming the battery is new or almost new, what should I do? Do I go for the second hand Mini Lama or do I crack my wallet open a little more and get the more expensive brand new one?

By the way, what's the durability of those tiny engines? They seem to be working awfully hard to lift the choppers and are incredibly hot after only a few minutes of flight... I wouldn't want to have to replace them all the time.

As far as which kind of heli to get, I wouldn't have an opinion.
But from personal point of view and experience, I suggest you stick with a new one.
You know how it's been handled and on the long run it might cost you even more fixing the old one if something you didn't know is wrong with it.