No, you would almost assuredly be classified as a dealer and need a license. Further, if your purpose in buying them was to turn around and sell them to a minor, you'd be in major shit.
But you're missing the point (one among many on this topic). There is a huge gray area. Buying ten and turning around and selling them for a 30% markup (like in your scenario) would most likely classify you as a dealer. Buying three guns over the last year and selling them throughout the year? You will almost assuredly be fine, assuming no other aspects of dealer characteristics (store, business cards, etc.). And that is the issue: the huge gray area without a set litmus test. It causes a loophole that people can legally manipulate.
You could go and buy three AR-15s in January, June, and December. Then, the following March, you could decide you don't want them, head down to the flea market, and sell all three of them for any number of reasons (just had a baby and don't want guns in the house now, desperate for money, need more space, etc.) and be perfectly legal not to check ID, get a background check, etc.
That is entirely legal (again, assuming there aren't other characteristics of being a dealer). If you don't see a huge issue with that, then you're lying to yourself. It's common sense that it shouldn't be legal.
