Education = Success
There are numerous "things" that go into any automotive project, that are far more costly, and involved, than parts.
One of the first signs that you are heading for failure is being overly concerned with the cost any of the individual "things," especially the things which are relatively inexpensive to begin with.
Please don't misunderstand me, I'm not saying you shouldn't sweat the details, such as the cost of individual parts, because individual costs add up, what I am saying is that if it really matters – and by "really matters," I mean that the cost will make or break your project – whether or not you spend an extra $100 on the cylinder heads, or $10 on that sensor, I can assure you, you are going to find failure looming on the horizon, and that you simply can't see it because you are blinded by a lack of education.
People – car enthusiasts, especially – have a tendency not to think through what they are doing, and don't want to consider all of the variables they don't understand, and can't see, because that is both scary, and challenging – and the truth is that inadequacy and difficulty both suck. An example, would be the cost of either knowledge or education (knowledge being a part of education as a whole, but education encompassing other elements beyond knowledge). If you are seriously concerned with the cost of that book, or that DVD set, you aren't ready to face the full cost of your education, which includes many elements both obvious to you, and hidden. And you sure as hell aren't prepared to execute that project if you don't have the necessary education.
A very common, concrete example is the cost of a repair manual. Seriously, if you're sweating that, you aren't going to succeed, because you can't afford the numerous other elements that you are going to have to have to execute that repair.
I'm not trying to be mean, and I'm not saying you aren't capable of going out there and getting them, what I am saying is that you may lack them, and it's critically important to recognize and accept when you do.
Ignorance is a brutal bastard, but it – more than most things – will dictate success or failure in any endeavor.