Dedekind said:Hasbro's operating margin is 13.5% and their net profit margin is about 8%. These numbers are not particularly crazy compared to other entertainment companies. Assuming that WotC's numbers are comparable to their parent (and they should be), I think I am comfortable with paying 13% of their costs to allow them to make more products in the future.
(I'm not sure what the mark-up is for retailers, but note that that 13% is not 13% of the cover price. It is 13% of something less than the cover price.)
The margin for your standard brick and mortar book retailer is somewhere between 41-43%, depending on your distributor (Ingram, Baker&Taylor, etc.). At first glance this number seems really high, but considering a bookstore will hope to turn over its inventory 1/year, it's not outrageous. For those not in the retail world, that would require a bookstore that stocks 60,000 volumes total to sell 60,000 units/year. The problem is that you're going to sell tons of whatever Oprah's latest bookclub choice is and have dozens and dozens of titles you can't move that end up taking up space (and costing you money). The margin is a hedge against these sorts of titles. It's also why you'll see chain bookstores offer 30%+ discounts off of bestsellers, since the assumption is those titles will sell in bulk. Even with these margins, Borders and Barnes & Noble posted very disappointing numbers for 2007 and Q1 of 2008 so it's not a cut and dried equation.
I certainly don't begrudge Hasbro the chance to make money. I'm semi-selective about what RPG products I buy (I'm trying to break the RPG collector habit) so if a product isn't up to snuff, I just won't buy it. In fact, my only real concern about 4e is that Privateer Press might not convert their Iron Kingdoms setting over to 4e. I'm happy to play IK as 3.5, but not having a setting available in the latest edition will make getting new players difficult indeed.