Yann Solo - I can easily understand why a modeler in this day and age would get frustrated by the variety - and cost - of aftermarket parts. I firmly believe that the 1990s and 2000s are going to be regarded some day as a golden age of scale modeling. There is more stuff available now to help kit builders produce outstanding miniatures than there's ever been before. And the quality of it is, for old fuddes like me who've been around since the beginning of plastic modeling, almost unbelievable. (I can remember without difficulty the days when good magazines and books were assuring us that radar screens were "unmodelable" on 1/350 or 1/700 scale, and guardrails were considered the exclusive preserve of veteran scratchbuilders with machine shops.)
All this becomes counter-productive, though, if it has the effect of intimidating the would-be modeler. Nobody suggests for one minute that a modeler "has" to buy three aftermarket sets - or one aftermarket set - to build a 1/350 Bismarck. Those things are tempting, but they're not essential. The truth of the matter is that the standards of detail and accuracy in the ship kits themselves have also been going up recently. (Those Tamiya 1/350 battleships are almost thirty years old now; a number of other companies have, at least in some respects, beaten them. But the Tamiya kits still hold up remarkably well.) A model built out of the box from one of those kits can be a thing of great beauty, and something to make its builder proud.
My suggestion is: take stock carefully of what you want to build, what you want the finished product to look like, how much time you want to spend on it, and what your budget is. I don't think anybody in this Forum has any intention of trying to force people to spend vast sums of money on their models, or scare them away from the hobby altogether. It's going to be your model. The materials are out there to help you complete it to a variety of standards, but all the decisions are up to you.
Youth, talent, hard work, and enthusiasm are no match for old age and treachery.