I am also prone to motion sickness. Even riding in the back seat of a car can do it to me. But, I love rollercoasters, go figure!

The ups and downs don't bother me, just the spinning. I bought the generic "motion sickness" medicine from Wal-Mart (equate brand, 100 tablets, 50mg of Dimenhydrinate) and while I can't remember how much the bottle cost exactly, I'm pretty certain it was less than $10.
I take these in the morning with breakfast (very important to eat!), and not have a problem the rest of the day. It did make me a little drowsy, but nothing bad.
I also find that I'm more prone to get sick if I haven't eaten recently or if I don't drink enough water.
What are these "Seabands" you speak of? Where can I get them, how much do they cost? Have they worked for you?