Thanks for the various opinions, facts and other comments on this subject. I am (as usual) especially impressed with the rational posts by Tom Geiger, Art Anderson and charlie8575. It's a complex problem. One thing I might add is that market research done by individual companies is not likely to become publicly available. It is expensive and is usually considered a trade secret -- there would be nothing to gain from giving it away, especially when competitors might be able to use it to aid in competing against the company that paid for it.
On the other hand, many of Harry P's posts, especially the ones stating that building a model not being educational, don't seem worthy of one who is a moderator. I'll side with the trio mentioned above.
I've built plastic models, mostly of cars, since I was a little kid in the late '50s. I've had "how to" articles on them published since the '70s. My career since 1982 has been with die-cast toy and model manufacturers in the new products departments -- and often being involved with people formerly with the model kit manufacturers. I know, at work I'm part of the "dark side" since the majority of die-casts are already assembled, sometimes have fad trends in styling that traditionalists abhor, and on and on. Still, my hobby is building models. I can't predict the future of the hobby but it sure is interesting.
I have the luxury of living two miles from a huge brick-and-mortar full line hobby shop -- I hadn't even realized it existed when I moved here (east of Los Angeles) fifteen years ago. It seems to be going great. It stocks the common kits and items that one would expect, plus it carries all sorts of obscure items (weathering powder, for example), has a big RC track out back and is staffed with knowledgeable people. The store manufactures (or, at least, store brands them) hobby items, too. So between this store and the internet, just about anything I could want can be purchased -- and then re-shaped by me into my own vision in scale.
Here's how to stretch your hobby dollar: take more time to build each model. Not only will the model be better, you won't spend so much.
A $40 kit plus $20 in paint/glue/etc. = $60 If you put in 60 hours to build it, it only costs a dollar an hour. You can't find much entertainment for that amount AND have something great to look at after you're done.
Spend 120 hours on it and the cost is only fifty cents an hour.
Ah, such memories. I had been building model cars since I was a little kid and kept on in my teen years when others' interests had moved on. I didn't have any money and my parents wouldn't consider my having my own car in high school ('68-'71). I grew up in the San Fernando Valley area of Los Angeles.
In junior high, the only hot car was a brand new '66 Chevelle SS396 in Marina Blue with a black interior that the janitor bought new. He parked it next to the shop buildings and we all drooled over it.
In high school, surprisingly there weren't a lot of interesting cars but there were a few oddities. One brother and sister each had Barris-customized cars: Albert had a '67 Malibu SS with a custom hood and spoiler with some custom paint. His sister had a custom-painted Opel GT with panels and lace. A guy in auto shop had a bare frame with a '50s Hemi and a kitchen chair welded to it so he could putt it around on the school access road. One of my buddies (non car guy) drove his grandmother's hand-me-down '62 Dodge convertible. It was black on black on black with rust, dirt a tattered top and the interior was filthy but it was sort-of cool in its own weird way. I did my senior photography project (10 minute slide show) on Van Nuys Blvd. cruising and still have most of the photos.
In my last two years of college ('74-'75) in central Missouri a guy living in my boarding house (similar to a frat without the frat stuff) was buying up Superbird, Daytona and any Charger/Roadrunner/GTX with a Hemi or 440. Remember, this was right after the first "gas shock" in '73 when people were unloading any gas-guzzler for a pittance. His name was Ed Burn (or Burns -- I may have the spelling wrong). I have no idea if he kept them long enough to capitalize on their huge run-up in value in later decades.
My college car was a 4-cyl. sub-compact. Oh, well.