Welcome Nicholas.
It is clear that you have a bit of learning to do about HT and tempering but we all started with incomplete knowledge.
There are several ways to go for you:
One is a forged blade blank, pre HT.
This option will allow you to shape the blade with files and sandpaper ( or a grinder if you have one). It will have to be properly HTed to harden, and unless you have a person or company that will do a hamon, it will be a plain surface hardened blade. Peter's HT will do a hamon. I think JT will do them, too.
Two is a forged and heat treated blade, but unfinished.
This is an unlikely thing. If a maker has already forged, hardened, and tempered a blade with a hamon, he will have done most all the work. He would just finish it and sell it as finished.
Three is a finished blade. You can get a cheap finished "tanto-esque" blade from places like Jantz or Texas Knife Supply ... It won't be Japanese style, and I don't think that is what you want.
You can get a finished proper japanese style tanto with hamon from some makers ... but they won't be cheap.
Your best way to go wll be to look over the makers on this forum, ans the ones in the Blade Annual or Knives magazine. Find ne you like and contact them about making you a blade to do the handle work and saya on. I, and others, here in Shop talk make such blades. I have sold san-mai blades that are hardened, but need the final sanding and plishing.
You have to be honest with yourself and decide what skills you have. Can you do yaki-ire? Can you do proper togi? Can you make a habaki or tsuba?
You have to ask what you can afford, too. At 19, you may not be able to afford many Japanese blades.
When you figure out all these things, then contact a maker and start a dialogue.
Also, do yourself a favor and fill out your profile. No one knows where you live, so it is hard to give good advice.
BTW, you will have to do all contacting and dealing by email or PM, as buyimg and selling are not allowed in Shop Talk.
