For what it's worth, while the TECEP Operations Management exam is difficult, it is passable. However, at $450 it's much more of a risk than taking a CLEP or a DANTES, and there aren't really any good practice exams that I know of. I managed to score a 74 on it (60 is passing), using the Barron's text and the VangoNotes for the Heizer and Render text. The IC flashcards are very helpful as well.

Still, if you have the time, taking a course is not a bad way to go. I would recommend you at least consider taking the course from the school you're attending. The cost may be somewhat higher, but you're supporting your school and there's a little less administrative friction. Plus, if it's Excelsior, the courseware will be quite good, and the schedule will be flexible and maintainable.

-Gary-