I get that same reaction from people all the time. Mostly it's people who really don't have a clue about the hobby, and have just heard from someone that toys are "worth something."
The people that ask "Are those worth anything?" get a variation of the response I gave a kid years ago when I ran a comic book store. He held up an issue of "Youngblood" and asked "How much is this worth?" To which I responded, "It's worth cover price to me, but if you read it and enjoy it, then it's priceless." He went away very confused.
There's not a purchase that goes by where I don't get either "Are you a collector?" or "You must like Star Wars!" I just smile at this point and humor them. Sometimes I tell them I'm a customizer and explain what that is, but if I don't have time I just make something up to satisfy them.
"I work for 'Troopers for Tots' and these are all going to a children's hospital in Lima, Peru."
Or something equally ridiculous off the top of my head.
Oh, and for the record, I wasn't trying to slam either JesseVader or Jokabofe in my responses, and I didn't take offense to anything they said. Still friends, guys?