While only you can determine if the money spent on a course is worth it to you, I can provide a few data points to help with your assessment.
The Big Nerd Ranch, known to many Cocoa developers for their excellent bootcamps and great books, has a 7-day Beginning iOS camp for around $4700 right now. They would be one of my first choices for a condensed training course, given how good of a teacher Aaron Hillegass is, along with the rest of their instructors.
The Pragmatic Studio also has a great 4-day iPhone training course for around $2000 taught by Daniel Steinberg and Matt Drance, two instructors I have a lot of respect for. I know several people who have attended this class with no starting iPhone experience that came out feeling they could build and submit an application.
As Nick mentioned, there is a load of great free content out there for learning iPhone development, in addition to many quality books. For a pretty good list of resources, see this question.
Check around at your local university or technical college. Many are starting to add iOS development classes, and these classes tend to be a good deal. For example, the Madison Area Technical College has a semester-long iPhone Apps Development night course for a tuition of around $350. The goal of that course is to take people with some programming background and have them building and running iPhone applications on their devices by the end of the term. I teach the complementary Advanced iPhone Development course there (for which the videos of last semester's class are available on iTunes U for free).