More often then not, software (apps) for OS X cost money. This was somewhat of a shock for me coming from Windows and Linux having not used OS X seriously for really any length of time at all ever. Generally speaking for Windows and (especially, and probably obviously) Linux, you can easily find free apps for most things. And in a lot of cases the free apps tend to be the best choices, or at least, good choices from the available options. There are obvious exceptions to that, e.g. Photoshop (Gimp is pretty bad no matter how you look at it I think).
I think I would be rather hard-pressed to find a Windows/Linux temperature sensor that costs $16. And even if I did find one, there are tons of other free options that are really good.
Finder replacements also seem to be a bit expensive for what they are and the only Windows Explorer replacements I know of are completely free, while Windows Explorer itself offers most of these things out of the box already.
Kind of hilarious that in OS X that one of the best ways (in my opinion, the only decent way) to get a decent mouse acceleration curve costs money.
There are probably some other options here (most of the ones I saw weren't that pleasant), but my god, the luxury of mounting EXT4 partitions in OS X has what I consider to be an outrageous cost. Funny that when I booted into my Linux install my OS X disk was available immediately without any tweaking.
Now, I'm only listing a few handpicked apps that I've noticed cost a bit more then I would've thought was reasonable. Most of these listed I've actually bought even though I'm whining about their cost here. I'm sure that for some or even all of these things I've listed, that there are probably some cheaper or even free alternatives. The ones I did find for some of these weren't that great though. I suppose you could argue in that case, that you're paying for quality. I guess I could begrudgingly agree to that.
Not saying that people shouldn't charge for their work. And to be fair, a reasonable price can be pretty subjective. I guess I just find it interesting when looking around for apps on OS X that do the same things I could do in Windows/Linux I usually find a price tag attached, where on the other OS's there was none.
It reminds me of this comic (from sticky comics):
Not quite the same thing (and a little exaggerated), but represents the mentality of the typical Apple user well enough I think.