There could be a long explanation to your question, but I will try and make it short and to the point, I hope. In some cases, the more expensive shafts do use more expensive materials and are built to tighter tolerances which can justify some of the price difference. Also, there is the marketing aspect. If the shaft is highly promoted and and also has the higher end materials, the pricing can get even higher. Are some of the prices justified? Not in my opinion understanding what the true costs are to produce a quality graphite shaft. That being said, costs of materials and transportation costs have definitely been rising which lead to prices that are higher. I have fit players into inexpensive graphite shafts that work well for them. I have also fit players into more expensive shafts that work well for them. In short, price does not equate to better performance. It may be that a $100.00 (or $350.00) option works best for you, but it may also be you can find just as good performance from a $59, $49, or $29 option. The proper way to know is to go through a proper fitting from a qualified fitting professional and find the specs you need. Then you can look at the various price points of shafts to see what the options are that fit those desired specifications (and your budget) and would most likely provide you the performance you are looking for. That would be for most recreational, avid or serious players, no matter the handicap. That being said, I do feel that a beginner or higher handicap player can be fit properly and are more often candidates for less expensive alternatives that can provide them good performance for where they are in their development.
Guess that wasn’t that short of an answer, but hope it helps.