I actually don't think it's appropriate to expense classes unless your manager explicitly asks you to learn a skill and you discuss and agree the best way is a class. We do not offer tuition reimbursement so just generally taking a class to get skills because they may be useful for work is on your own dime, like someone on the business side getting an MBA.
Classes. Cheap and you can learn a lot. My bro got a job at FB ramping up his skills with classes from there. They often have classes for $10 that are highly technical and taught by really good teachers (read the user reviews fire the class before purchasing-they also have video previews of the class).