It's not, when you think about it. But, to defend our hypocrisy, I will say while just buying the parts usually takes you well in excess of $20, the end result is something you can't get elsewhere. You get to decide the exact figure parts (and this is definitely true when it comes to custom cast torsos), accessories and paints.
To put it another way, I've yet to see a mass-production 4" figure that I've deemed to be worth $20. Hasbro and Mattel will never come correct on that score.
To put it another way, I've yet to see a mass-production 4" figure that I've deemed to be worth $20. Hasbro and Mattel will never come correct on that score.