Philodendron x evansii
Rockledge Gardens on US 1 near Cocoa has had Philodendron x evansii,
sellowianum, a 'selloum improved', perhaps eichleri, and a couple of other
large self-headers in the past. These were in 1 gallon nursery cans for about
$9. Last time I was there I did not see them, but you might call and see if
they're going to stock them again. They've had them for a couple years now
off and on.