You know the rast, right? That often-maligned, rarely-used, what-the-heck monster from the MM? I finally found a use for them.
My wizard is going to use lesser planar binding to call one. Then kill it with phantasmal killer or something similar, then animate it as a skeleton. Since a rast's flight is a magical effect, the rast skeleton will be able to fly. A cheap flying mount with 60' good flight!
This works on nightmares as well, but my wizard is a gnome and would rather have a Medium mount. A ravid is another option.