Walk ups to BOG are as rare as seeing Beast in the park.
However, it's amazing the number of last minute cancelations there are to BOG. Be sure to check the
MDE experience one or two days out and while you are at WDW. I find the best times are after 8:00 pm or before 6:00 am (Eastern). Just checked the next two days and there are three breakfast times available both days and a lunch for the day after tomorrow.
The key is persistence. Keep looking and you'll make your own Pixie Dust.