You can indeed transfer to/from alpha accounts, I have done this many times.
As Zoltan said you purchase 1000 plex and move it to your plex vault. You then open up a support ticket in the Character Transfer group. To speed things up, include a link to your character bazaar post, and of course the destination account.
Expect a 1-5day wait
EDIT:
You can even recruit yourself, and transfer the character to a fresh account with 0 toons and redeem the 250k free SP on that toon, despite it not being a new toon.