1 - agree

2 - there should be some sense of what it actually cost to make it. What will happend if all gas providers decide to increase the prices with 200% because the market can bear it.
3 - it depends, but you are correct about many of the products on the market. My idea was that adding to the cost all design, manufacture, package, material it still sound too costly to me. Maybe I am wrong about it.
Fixed natural products like gas aside since the are limited.
For items such as your waterblock supply is practially unlimited within reason.
If you charge too much someone will enter the market place as they are no barriers to entry. You could quickly setup a business manufacturing copies of their blocks, but run the risk of a lawsuit. Say you come up with your own new design thats better than theirs, you have sub contract manufacturing so no massive initial outlay, what would you charge?
They will react to you, either lowering price, maybe creating a better product at the same price etc.
Practically everything evolves, long terms players will typically stay, new upstarts will join and either go ultra niche or try to develop into a larger long term player. If the new upstarts are rocking the status quo too much they may well be bought out, or their business model atacked (think loss leaders etc)
People go into business to make money, most do, some dont and will disappear. Typically if your relatively mainstream and you make good profits sooner or later someone will come and challenge your position. If there is genuine customer demand for a product multiple people will always try to supply it.
Think of tablets, if tomorrow demand was only 1% of what it is today do you think there would be such effort my most tech companies to make marketable products (by marketable I mean on quality, price etc)
The key is perceived value, if you are happy to pay £100 for something but its £200 then you coul dbe annoyed that in theory its only worth £75 of materials and they are "overcharging". If you would be happy to pay £500 and its cost was £200 you wouldn't even think, you would just buy and move on.
One of the best examples is cars, I haven't seen any details for sometime, but the bottom spec models were often breakeven/loss leaders, as you went up the range the differentiation (bigger engines etc) often came at a much higher premium (sometimes as much as 10 times over) than the actual added costs. Take optional extras, they are well well out of balance compared to the car in the first place.
How much do you think it would cost to design a new car, yet the actual value of the parts when broken back down to their "raw" materials is probably 2-10% of the price you would pay new for the main consumer vehicles on the forecourt.