Those TVM poor boy kits make a great looking rifle.
Tools are important, learning to sharpen them and use them correctly even more so.
Unless you live near someone who has built a rifle or two the next most important thing would be books or CDs on building rifles.
Like Wobbly said it's a fairly large investment but can be broken down by buying over a period of time.
Some choose to buy a rifle "in the white", meaning the rifle is assembled but the metal is not finished.
Guns "in the white" cost a little more but you can go shoot them as is.
This allows you to apply whatever type finish to the gun you like or just let it age on it's on.
If one chooses to go another route instead of a "kit" from a manufacture.
You're looking at $175 to $200 + for a barrel, locks run around $175.
The side plate, butt plate, ram rod thimbles , sights and misc. screws and such will run another $100 or so.
Stock blanks cost varies depending on the "Grade" , the more fancy "curl" the more expensive.
Also the more work such as inletting the barrel and lock the manufacture does the more it cost you.