To start, it goes without saying that this shaving hobby is typically not a money-saver, even if it's pushed as such by enthusiasts trying to convert people to this style of shaving. Looking at the price of shaving soap using price per oz. is fairly common (I still do that sort of thing even when I'm in the grocery store), but die-hard hobbyists tend to scoff at it, because, well, you sometimes get what you pay for.
With that being said, there are people all over the world with varying budgets, and like any hobby you can spend as little or as much as you want. From Col. Conk to Sebum Gold, there's a wide spectrum of cost for shaving soap.
In this recent video from Stirling Soap Company, Rod talks about how tubs are the most cost effective form factor. Samples and even Refill Pucks are more labor intensive, making them more expensive per oz. You might assume, as I did, that a refill puck would be cheaper per oz. because it doesn't come with a plastic jar, but you would be wrong.
But wait! Take a look at Barrister & Mann. They recently lowered the cost of their samples to $3.99USD, and their samples are a full 1 oz., just like Stirling. That makes them $0.11USD cheaper than Stirling samples.
Now lets do some math.
5.8 Stirling samples to make one of their shaving soap jars: $4.10*5.8 = $23.78, a lot more expensive than just buying a jar for $14.24USD.
4 B&M samples to make one of their shaving soap jars: $3.99*4 = $15.96, a whopping $9 cheaper than buying a tub for $24.99!
Does a tub, label, etc. cost $9 extra? Are the samples a loss leader like rotisserie chicken and hot dogs?
Either way, it's great to have both of those companies offering generous samples. House of Mammoth also has relatively large samples, but they're 1/2oz for $6.00USD.