I'm sorry, but I just don't swallow the notion that rising oil prices justify or explain major rises in the prices of plastic kits. The truth is that materials make up only a tiny percentage of the price of a plastic kit. For that matter, the cost of production is only a small part of the price we pay for the products.
I'm not sure how things are now, but when I was working in a hobby shop (quite a few years ago) the standard retail markup was 40%. That is, when a customer bought a kit for $100, $40 went to the shop. The wholesaler took another chunk (I don't remember exactly what it was, but I think it was something in the neighborhood of 25% of what the retailer paid the wholesaler - in other words another $15 in the case of a $100 kit). So maybe - maybe - $45 of the $100 price of the kit made its way to the manufacturer. Deduct from that the price of the box, the instruction, the decals, and all the other non-plastic stuff that's in the box. Then deduct what the manufacturer pays its employees - from the designers to the folks who load the boxes onto the trucks. Then deduct the enormous prices of the molds. I don't have figures on any of those expenses, but my guess is that the actual plastic that goes into a $100 warship kit costs the manufacturer less than a dollar.
We went through something almost exactly like this back in the early 1970s, with the Nixon/Carter era energy crisis. At that time, as is the case now, the hobby was going through some big changes. Companies (e.g., Aurora and Frog) were going bankrupt, and the survivors were giving up on serious scale models (except cars). For several years during that period Revell and Monogram didn't produce any scale airplane, ship, or armor kits; they devoted their efforts to products like "Snoopy and His Sopwith Camel" and the Goodyear Blimp (complete with electified signs to be colored with felt-tip markers). The factory reps who showed up at the trade shows and IPMS conventions tried to claim the reason was the price of oil. The truth was that the traditional markets for plastic kits were changing. Young kids weren't buying airplane, ship, and tank kits any more. They were watching videos, playing games on their new-fangled Commodore computers - and smoking pot.
The eventual result, though I suspect lots of adult modelers didn't see it happening, was a fundamental change in the hobby - and its pricing structure. Plastic modeling nowadays is almost completely an adult hobby. At least half of the clientele of the shop where I worked, back in the mid- to late seventies, consisted of kids. A few months ago I asked a friend who runs a fine shop in Tidewater Virginia how many of his customers were under the age of 20. He laughed bitterly and said, "zero."
Why don't kids build models any more? I guess there are lots of reasons: competition from computers and play-stations, athletics, cable tv, sports, and various illegal activities undoubtedly is a big factor. But another one is money. I can remember when a dollar would buy a model, a tube of glue, a couple of jars of paint, a brush, and a Coke at the soda fountain in the same drugstore. Take a look at the stock in your local hobby shop. You'll find it difficult to find a kit - even a 1/72-scale fighter - that costs less than $10. The prices of plastic kits have risen considerably faster than inflation. The typical kid, even in the twenty-first century, doesn't think of $10 as pocket money.
The flip side of the coin, of course, is that the average level of quality has risen along with the prices. I can remember when 1/48-scale aircraft kits with countersunk detail were hard to find - and the only Japanese warship kit for sale in the U.S. was that awful old Aurora Yamato. The vast range of kits, paints, tools, and aftermarket parts (virtually unheard of when I was getting into the hobby) testifies to the fact that it's an adult hobby, supported by knowledgeable enthusiasts who are willing to spend considerable amounts of money on quality merchandise. It's really a different hobby than it was in the fifties - or the seventies.
I suspect we're going to see some more big changes during the next few years. I see some signs I don't like - and others that I do. There are all sorts of legitimate reasons for the nature of the hobby to evolve. But rising oil prices isn't one of them.