The prices charged by GW can't be boiled down to something so simplistic. There are a huge variety of reasons for why the price points are as they are. The money spent on the renting of stores, paying the wages of the staff who work there, making sure there is the stock available to fill those stores, transporting the stock to those stores and sundry others expenses I wouldn't know about- these are just a small portion of the money GW spends.
After that, or before it I suppose, you have the huge amount of cash that is spent on R&D for new plastics technology, the plants used to make the moulds/inject the plastic, the place where the kits are boxed-up, the money to pay the staff in these places, the cost of transporting the boxes to and from these sites to the stores...
Then there is the cost of the main studio and all of the creative people who work there. Probably the most onerous commitment is the interest the company will be paying on their bank loans.
It is a complex equation for the comany to work out how much they will charge so that the product remains affordable and, yet, turns a profit that allows the company to grow. The prices GW charge are, in my opinion, fair for what you get. Others don't think so and that is fine. But what would be really beneficial is for people to actually look into the economics of the GW situation, or just economics of markets in general, and get some idea of how the world works (price rises each year happen because of inflation and by the banks raising their interest rates, this latter being the one with the scope to cause the most harm). GW is far from having a monopoly on models, although I agree that, for the most part, they are some of the best.
If GW did have a monopoly (virtual or full), then there are laws that stop comapnies in this position from gouging customers with massively inflated prices. And no, you can't take advantage of these laws because they wouldn't apply to GW, partly because they don't have a monopoly and partly because the purchase of these items is competely volountary as it is a luxury item (IE one that is useful only for fun/recreation).