Please. So paying the same money for a 24" comparably equipped machine from HP, Dell, or Sony is considered what? You get what you pay for pal. Apple's pricing is right in line with comparable products.
There is no Apple "tax". They just don't participate in the low-margin bargain computer market nor computer designs they don't like. For the most part they only sell mid to high end machines and have a great business doing so. The exception is you can get a much better deal on a tower computer with equivalent sized monitor from HP or Dell, but Apple rejects that design for their mainstream products because it goes against their philosophy of simplicity in function and design. And yes, you will pay a little more for design and the excellent support that backs their machines. If you don't care about that, then I encourage you to buy from another maker, but don't make up your own reality about a "tax" that has no bearing in facts.
Of course it is safe to by the 27" iMac, we have several here at work and they are fantastic machines. Apple has sold more than 1 million of these machines already. Yes, some small percentage have had problems, which is too bad, but that is true for nearly every product you can buy.
whilst not ignoring the rest of the mis-info. you posted (it'll wait) care to shed some light how you come by those figures?
I'd hazard a guess its not even close...