Jared Padalecki and Jensen Ackles are in the UK in May anyway and I would love you forever if they were guests at Collectormania too!
Other guests:
Michael J. Fox (I can dream...)
Christopher Lloyd
Crispin Glover
Helen Slater
Margot Kidder
Nathan Fillion
Milo Ventimiglia
James Callis
Tricia Helfer
Gary Cole
Henry Thomas
Seth Green
Wow, I can go on...