I did some research... the ticket is valid, but its a $45 ticket, not $55.

In general, its bad form to try and scalp tickets above cost in this community, even if the current cost is higher. The lower tier prices are provided as an incentive for people to get involved in Decom earlier in the year. People who buy earlier, are usually more prepared and participate more in the event. They aren't provided as a way for people to subsidize their own ticket price by selling them later at a higher cost.

Of course, maybe there's some $10 cost that you incurred that no one else did, but it sure ain't taxes.