My problem is the particular models I like to build (Pocher).
They're not made anymore (the company went out of business years ago), and unbuilt kits are getting harder and harder to find. And of course, as the remaining unbuilt kits are sold, the prices keep going up, up, up, because there's only a finite supply of them in existence.
I buy to build, not to "collect" or to resell at a profit... so every Pocher kit I buy and build means one less on the market, and that only serves to drive the price of the remaining ones up even higher. So by buying and building them (thereby reducing the number left to sell), I guess I'm actually part of the reason the prices keep climbing!