Yes if you opt for a character breakfast it is cheaper if you are staying onsite as you are basically upgrading from a normal breakfast to a character one.
Some people think its a waste doing a character meal then as you already have breakfast included but we've done it twice and really enjoyed it.
The first time we did the early sitting and the 2nd time the later sittng. I much preferred the later one as I dont like eating early anyhow.
We went into the park for an hour for EMH and then went back out for breakfast. - its amazing how EMH builds up an appetite and we didnt feel we wanted to rush to get into the park as we'd already done lots of rides.
So we lingered over breakfast and found we didnt need any lunch that day either