I am there (as long as I have that notice you mentioned...for someone in my position a couple of months or more notice would be helpful).
Angela's suggestions are great...especially that part about not sitting around all day.
It would be cool if Erin set aside some time for in person readings on the days surrounding the workshop (if that's even possible). Maybe she would have a couple of days where she only does readings for people who came in for the workshop??? I would show up a day early for that.
Highly interactive is great, $300.00 sounds very reasonable. All in all I trust that you guys would make it a very worthwhile experience.
ETA: The reason I voted "I'd probably attend" is just a matter of getting the time off work