You can take the bicycle into the store, just mention the reason for doing so to the customer service desk-or store management.
I can almost guarantee that they will welcome you and often store staff offers to help because they enjoy seeing the odd sight of a classic bike in the store.
I did this at a Home Depot years ago while searching for an off-the-shelf Yellow that was the closest match to the early Seventies era KOOL LEMON Schwinn color.
Years ago, around Thanksgiving, my brother who at that time had a MIATA with the hardtop up on it, that had a scratch/paint chip on the hardtop from being stored in his garage, since the hardtop wasn't used very often except from late Nov to mid Feb. He kept going on and on about the stupid paint chip on the hardtop's roof that you could barely see, and my sister said, oh will you please just shut up with this, as it is a damn car and you can just go to Woolworths or Eckerds and buy a $2 bottle of nail polish that will match and fill the chip. There must have been a reason, probably to entertain the kids, or something but half the group, two packed cars, followed my brother's Miata to the Eckerds Drug Store about three miles away. The girl working at Eckerds said to us, is the car parked outside? lets go outside and see it upclose to see if we can find something that is a match. She said this is fun, and after pondering over about six different colors, she said these two from different brands should be about the same close match. My brother bought the color that the majority of the group said was the one to get. It perfectly matched and self leveled in the chip.....just that nail polish and some assistance from a new unhit wooden golf tee with a clean sharp point. I don't think he would have been able to get a perfect match without going upclose to the car, and having the benefit of several different pairs of eyes viewing and providing their opinion because there were so many possible color choices and it is difficult unless what you are trying to match is right there.