[Crazy Jetty]

Trust me. No one cares that you're buying toys. There are plenty of adult collectors in the states (Assuming that's where you are. Forgive if otherwise).
And if anyone does say something negative to you about it, like some nosey cashier, tell them (politely) to mind their own business.

But like I said, no one really cares. And on top of that, it can be a fun experience when you stop caring about if others are looking down on you or not. I've helped hopelessly lost parents get what their kids want, and I've had fun conversations with other collectors and kids.
But anyone who'd be snobbish to you, look down their nose at you, or judge you are hopelessly shallow, and their opinions shouldn't matter to you.