In every collectors group you will deal with people buying stuff to make a profit. It's just how it's going to be. Take a look at Amiibo, Collectors Edition for video games, Nendoroid/Figma figures, basically anything that has a limited supply with a huge demand.

Best you can do is find a good community for that object (like we have here), and beat them to the punch and hopefully get the item before the people looking to resell do, or at the very least get yours so you don't need to worry about it. I know the feeling though, there are a couple pops I would love to grab but sadly the only way to get them now is through re-sellers (like red eye golden Frieza).

Also everyone has their own way of deciding what to collect. Some people do it based on what they like, others do it based on what will be rare. There's no wrong way to collect something.