Bluntly put - it ain't none of your business. I've had to fill out "multiple purchase" forms more than once, simply because a certain set of guns caught my eye. It ain't about "need" - if I'm a law-abiding citizen, you have no say in how many guns I buy at one time. Period.
Now...I realize the above sounds harsh - please do NOT take it personally. I said it that way to emphasize the point I'm trying to make - that it's my choice to spend my money however I wish. Having said that, I also realize that there ARE folks out there doing "straw buys" - and where you KNOW it's happening, I'm all for stopping 'em. Just be careful - some of 'em may be doing so at the direction of federal agents....
+1