In my opinion only and based on my budget and my strong dislike of over-inflated prices, fair prices for an Aristocrat in excellent condition (depending on your definition of excellent):
Razor and blade holder only $40-$50.
Razor, blade holder, and case: $60-$75.
Razor, blade holder, case and shipper: $100.
You also need to be clear about what you mean by "50s". There's the 1948-50 model, there are a few with the V3 date code placing them squarely in 1950, and then there are British models which have specific dates as well. Those might command more money.