It's actually better to take a class your unfamiliar with in a practice match first to learn the basics of it before doing anything. It only takes a few minutes and can save you some trouble in an actual game. From enemies and upset team members all together.
How much is the S. SMG going for anyway?edit: nevermind I realized I derped and that was already answered.Just for convenience. http://tf2spreadsheet.blogspot.com/
If your looking for players to practice with or team with I'd be willing to let you tag along with the team I usually play with. We usually have a Wascot, Cheston, Healer, and Veteran/Gunner to let you know ahead of time.