So I've been away from these forums for almost two years (bad me!), but I recently started lurking again, and when I saw this post I had to reply.
This will be my third year going to DragonCon, and I was obviously thrilled when I saw Dean's name added to the guest list.
But to answer your questions... yes, in order to get into the Walk of Fame which is where the actors sign autographs, you need a Con badge. For the whole weekend (Fri-Mon), badges are $120 (available to pre-order online or to buy on-site), or you can also buy one on-site for just one day ($40 for Fri, $50 for Sat, $40 for Sun, $30 for Mon when a good number of the guests have already left).
I don't know what Dean will be charging specifically for autographs, but I've seen autographs costing anywhere from around $15 up to $60, maybe higher for some of the really big names. The majority seem to run around $30 or $40, and I would guess Dean's would fall somewhere in there.
Hope this helps, and hope you make it to Con!
Let me know if you have any other questions, and I'll try and answer them.
