It's pricey, but I LOVE it. I suppose most people buy it after soaping a long time, but I bought it right off the bat to help me keep track of the money I was putting into the hobby.
I love how I can save my recipes, compare recipe properties (hard bar, fluffy lather, moisturizing, etc.) on the graph, track inventory, and even run reports to see where I spend.
It tells me the actual cost of a batch, and the actual cost of each bar of soap (depending on your soap size, of course.) It lets you add in everything from colorants, EOs & FOs, and any other additive you can think of. It also lets you add in the cost of your packaging. All of this together lets you know your actual materials cost...minus time & labor. But that's easy to estimate, IMO.
Can a free spreadsheet help you do all this? Sure. But I'm excel illiterate, and this software let me do everything with little to no learning curve or stress.