Unfortunately there are many different factors that determine the price of a shaver (other than unscrupulous things like price gouging or selling loss-leaders). Everything from where the shaver was made (Germany, US, China, etc…) to the features, functionality and accessories it contains (cleaning systems, pulsing head frames, water-cleaning, etc…) to the company name which many people associate with levels of quality (Braun draws a higher shaver-quality rating than Wahl, for instance).
For the average consumer I recommend staying along the lines of what has worked for you in the past, carefully consider “bells and whistles” if you don’t really need them, and understand that when considering the lower-end machines that you do get what you pay for. Really.