I'll second what just about everyone else has said: go for it! You can do it!
There are lots of ways to get your feet wet. Buying blades from Jantz wouldn't be a bad option. There are several tricky skill sets involved with knife making -- and making a really good handle is one that is often not mentioned. Starting with someone else's semi-finished blade and putting really good handles on it will give you a sense of accomplishment, a very unique and useful knife, and a feel for working with the blade.
It is amazing how many different ways there are to accomplish basically the same thing, and starting from an
entirely clean slate may lead you to some frustration. You really should study the work of others. We've all had knives, of course, and know a bit about them, but once I started assembling, disassembling, adjusting, and otherwise modifying blades and whole knives made by others, I realized that there was SO much to learn about the tiniest details.
How does the tang work inside the handle? How does the sharpened edge meet the tang? Does it have a guard? A choil? Why? What shape is the blade, especially the tip -- and WHY? How much length is there between the front of the handle and the start of the sharpened blade, really? Why is that much unsharpened length present, and what did the maker do with it? How will that affect how the blade is held or how it can be used? What is the angle of the edge when the knife is held in the hand? WHY? What is the angle of the spine of the edge to the handle, and why? What is the thickness of the blade, why, and how does that affect the weight and balance of the knife? Is the blade tapered at all? And, again, WHY?
As I've started making blades entirely of my own, I've run into points in the middle of a build where I realize part A and part B (that I really like) don't meet in the middle quite the way I'd intended, or that I didn't leave enough real estate somewhere to accomplish something I thought I wanted to do -- either leading me to develop the shape in a different direction, or sometimes... well, to the scrap pile!
So, while you absolutely can start with some steel and some handle material and make your own completely organic knife, there is a lot of value in taking things in smaller bites while you educate yourself.