The career path to become a college professor can vary according to your qualifications and experience, so there are a multitude of directions to consider. While many years of higher education are needed, there are many other requirements that a college professor must meet.
Publishing and Teaching
While I don't want to create a natural opposition between these two areas of academia - publishing and teaching - the fact of the matter is that certain schools will usually privilege one over the other, even though they may require experience in both before hiring someone into a professor's position. Typically, a community/technical college is going to place more emphasis on the teaching aspect of the professor's job and experience since that college is going to require their professors to teach more courses than a professor at a research university. 2-year colleges often make their money off of employing large groups of people, so they have quite a teaching burden to meet. They need professors who can teach at least 4 courses a semester along with the other committee work that is needed.
As you might imagine, the 4-year university is going to place a larger emphasis on research, which brings prestige, grants, and the brightest students to its institution. The pressure to publish or perish, as it were, is increasingly necessary at the Masters and Ph.D. level, even before one gets a job as a professor, again, a career no longer of critical shortage but rather of high supply. In order to snag a tenured position at a four-year college, one has to distinguish oneself from others by publishing and sharing papers at conferences. It would be best if scholars-in-training would spend more time producing high quality publications, but it is sometimes difficult in an environment that seems to value quantity over quality.
If you think that you would like to teach at the college level, you should decide on what kind of college at which you would like to teach. This will ultimately determine the career path to take. If you want to be a professor at a community or technical college, you will need at least a B.A./B.S. (undergraduate degree) as well as an M.A./M.B.A./M.F.A. (graduate degree) in order to be qualified to teach at that level. Overall, you're looking at 6 years of college in order to teach at the community/technical college level, although some of them may show a preference toward those with Ph.D.s.
If you plan to teach at the 4-year university level, including at any research university, then you will need a Ph.D. in order to meet the requirements for any full-time lectureship, visiting assistant professorship, or tenured position. A Ph.D. program usually takes another five years beyond the undergrad and Masters degree, for a total of 11 years of schooling beyond high school. Only a few of those years, however, are devoted to coursework in most cases.
It is difficult to even ballpark a price of the education necessary to become a college professor. The years listed above will serve as a solid reference for you to look up tuition prices at the schools you are most interested in to give yourself some sort of estimate. Also, financial aid in the form of fellowships and graduate assistantships are widely available and can dramatically reduce the price.
Although this is another topic altogether, it is worth mentioning here. Graduate assistantships are paid jobs (usually with partial or full tuition remission) in which a Masters or Ph.D. student teaches courses or performs some other academic duty for the university in exchange for free courses and a yearly stipend. These assistantships, while many don't pay that well, do offer graduate students with the opportunity to gain invaluable teaching experience that will help prepare themselves for a career as a professor. While these assistantships are highly competitive, they are worth applying for and committing oneself to.
While the career path to become a college professor can easily take over a decade altogether, it requires much more than just attending classes and doing the bare minimum. It challenges an individual to become an expert in a given field, learn to teach competently, and enter into a scholarly discourse through publication and public speaking. With tenured positions becoming more and more scarce, the decision to choose being a college professor as a career should not be made with haste. Consider all of the work and time involved and weigh that against the self-knowledge of whether or not this is what you are meant to be.