They usually have cash prizes, or at least electronics.

In a lot of big companies, there is always a huge distrust in the management.

Seems to be true even cases like Google and Microsoft.

That is having too many expectations. You should go into this expecting them to give you a small bonus. That is it. You don't have some idea you value at under $1000?

Doesn't seem like a good deal

It depends. I am someone with a lot of ideas and I will never follow up on 95% of them on my own accord. Having it on the resume + the $200 bucks is more than enough for an idea that would otherwise just rot in my notebook.