I think that it is entirely dependent on what you insurance plan is. I just got new insurance and spent a good deal of time on the phone with them trying to figure out what would be best for me.

Usually (again, check with you plan) if there is no generic available for the drug they charge you less than if there is a generic available. You can check about what their policy is for "specialty" medications, because that will offer you more insight than any of our guesses. The specialty meds normally fall outside of the typical Rx plan. I think the vast majority, perhaps all of the dmd's are brand name only. You could ask what your insurance would look like if you stick with your generic plan and need to start taking one of those.

Also, the drug companies know that their stuff is expensive and many have patient assistance programs. I'm on one for my Copaxone right now, and it is a HUGE help and required relatively little paperwork to enroll in.