There are a number of things to consider, when we talk about the price of model kits, especially if we compare prices to where they were when we were kids-that can be 40, 50, 60 years in the past for many of us.
General inflation over time, for one.
The price of petroleum, which is used to make the styrene.
The price of tooling the molds.
The fact that the manufacturer has to take into account how many units he can sell, at a time when there are fewer people buying the product-even allowing for different levels of demand in different parts of the world. He needs to recoup his costs and make a profit, or, he doesn't make kits anymore.
Also we need to recognize that this is a hobby, so it's discretionary income.
Having said all that, the prices can impact your tastes and decisions. I'm more of a nostalgia modeler, for example. That is, I like the brands I had when I was a kid, like Monogram, Revell, Lindberg, Aurora, Pyro. I do buy new models, but again, my tastes determine what I buy. I don't really build armor today, mostly airplanes, and my preferred scale is 1/48. With an eye to prices, I like Airfix and Eduard. I have also bought Dora Wings kits, balancing the price against the unusual subjects DW puts out.
But I have also bought a lot of kits on the secondary market, where prices are negotiable. So, eBay (can't really negotiate there) but also at shows, club meetings, through forums and social media (where haggling is more often part of the process). And I've got rough guidelines that I follow, approximate prices I'm willing to pay. For second-hand kits, if I can get a single-engine 1/48 aircraft for $10 or less, I'm happy. Multi-engine kits, like Monogram's kits from the 70s, I'm willing to go to $25, but most of the ones in my stash I got for $10. My coup was 2 B-29s and 2 C-47s at the IPMS Region II show in Cherry Hill NJ about 10 years ago or so. Ten bucks each, marked down from forty each, because it was the end of the show, and the seller didn't want to take the kits home. I was very happy with that one.
People will say that building models is too expensive for kids to take it up, the way many of us did when we were kids. And it's true, prices are higher, but there are still bargains to be had. I mentioned Airfix and Eduard earlier, which can be had at reasonable prices, and are nice kits as well. And supplies-tools and paint, glue, for example, can be found at reasonable prices. Again, it takes some thought, some preparation, but it can be done.