Is there a way to get KSP free legally or at least, really cheap?

Hi everyone. I'm [snip] craving KSP. So I did the obvious thing: I asked my parents. Fortunately, my birthday was only a couple of weeks away, and my mom, who was in a good mood, said yes and that she will consider it with dad. After that, the days and weeks went away, and here came my birthday. Now, I wanted KSP more than ever. BUT my parents didn't buy me KSP. Or anything. I was pretty depressed. It wasn't like I didn't tell them. I told them what I wanted, and they said yes! Now it's been 3

As a parent, I can say that you have to look at it from their perspective. Gaming often gets lumped into one massive category. I was also cautious about purchasing 'certain titles' for my young ones. Please understand that. Explain to them that this is basically a physics-simulating lego set. Take the academic aspect, and sell it that way. Explain to them that some on this board, like myself, are older than they are (possibly 2×) and have backgrounds in mathematics, science, engineerin