Collectible is collectible.
When you summon the Exclusive San Diego Comic Con Chandra, nothing special happens. It costs the same amount of mana, it has the same loyalty and the same abilities. In fact, the only difference is that instead of looking like this,
It looks like this,
That's it. So why is the Comic Con Chandra worth so much more?
OK, that was more "Socratic method" than "I don't understand finance" because I'm trying to make a point. Rare and exclusive is valuable and worth having if you can get it. This was firmly in mind when I saw that Pop had released a line of Magic collectibles.
Probably not a much more prudent investment than those Beanie Babies your mother was going to retire off of. Still, they look cool, and they are Magic-themed. So what was that about exclusivity? Only this.
Hot Topic has an exclusive Chandra doll that they sell on their website and possibly in their stores that GLOWS IN THE DAMN DARK.
Are you impressed by stuff that glows in the dark? I'm not, but I don't buy action figures, either. Still, while I don't think the "buy sealed product" wisdom applies to these pop toys, if you are going to buy one, buy an exclusive Chandra that glows in the dark. That's a no-brainer.