I got my passport several months before a trip to Australia I was planning. I lived in the US at the time. It cost me just over $100, and I got the paperwork at the post office. They had an office I could go into, to both get the paperwork, and then have them look over it, and take my money, before they sent it on. It was maybe a week or two before it arrived back, with my new passport.
Generally, you need two small passport photos (I bought mine at Walgreens for $7.99), your birth certificate ($13 dollars for a copy at the town administration offices for Deaths, Births, and Marriages), and all the paperwork filled out as correctly as you can manage. (This was for a California state resident, so other states will probably vary.)
Overall, the wait time wasn't bad (though it did take me a while to get the paperwork finished, simply because I had to hunt for my birth cert, and then get a copy of it.)
By all means, though, plan a trip! The paperwork will ask what you need the passport for.
Also: order the full passport booklet, NOT the passport card. The passport card costs the same amount as the booklet, but limits you to only Canada, and a couple of other places, rather than everywhere else. For that price, you want access to wherever you want to go.