All the things you have said are true if we believe what we are told, however take a look at Frontline: United States of Secrets (On Netflix now) and you will see that the NSA has been capturing phone calls, texts, internet searches, purchases, etc. on millions of Americans and storing it (They still are doing so. They interviewed top officials in the NSA, the Justice Dept and the White House and they all admit it). And they have invested billions into software and hardware, so it is likely that they are aware of the purchases we have made/make. And they and the ATF keep up with the buying and selling on these type websites as well.
So I suppose it's really a matter of whether we think they really are interested in what we are doing and why? If you believe they are good folks just trying to protect us, then there is nothing to worry about? If you think otherwise, then you may have reason to be concerned? I'm sure I'll get some hate mail for saying this, but the more I research how much they really do know and track, the more I realize how much I really don't know!
So I suppose it's really a matter of whether we think they really are interested in what we are doing and why? If you believe they are good folks just trying to protect us, then there is nothing to worry about? If you think otherwise, then you may have reason to be concerned? I'm sure I'll get some hate mail for saying this, but the more I research how much they really do know and track, the more I realize how much I really don't know!