Isn't this always a hot topic and a difficult one to balance.
The only way I can describe this situation is like with cars.
You can buy a car for £10,000 that will get you where you want to get to, be reliable, look ok and certainly do the job. However, you can also buy a car that costs over £50,000, gets you there as well, is reliable and also looks the part.
The only real difference is in the engine and the interior, yes,granted looks may be a bit flashy but thats just visual.
Likewise with WFP companies. YES without doub't you can set up your own system or go to a supplier and purchase a set up for the region of £1,500. The system will be able to do the job to a high standard, will be reliable and easy to maintian, depending on how it is installed it will look nice as well.
However, you can also go to a high end manufacturer, purchase a system for say £3,500 upwards, it will do the same job and also be reliable. The difference is it will be visually probably more attractive, possibly built with stronger natural materials and may be put together in a slightly neater format.
The real thing to remember is this, for every person in this world we are all unique, we all have personal thoughts and opinions regarding everything. Therefore, companies and manufacturers can tailor their products to suit their potential market place and demographics.
Personally I am happy to sit in the middle of this. I use some DIY products as well as High End manufacturers. It really is down to choice.
I think they are only a rip off if they are the only one's in the market place and command rediculous prices, in reality we do have several "other" options.
Best wishes,
Trev