Your company standards should apply to what you do
and how you work.
I would never buy someone else's standards because they will never work for the way we do business. Even if they are free, they won't fit and you will spend a lot of time (and money) interpreting the meanings of the standards. This is not a one size fits all. Cad standards (in my company) is a forever changing/living document. As needs change, software changes, and technologies change, the way we do drafting has to change as well.
Take the time to develop your own Cad Standards based on your business, your business needs and your customers expectations. Good cad standards should be short, concise and easy to understand. In other words, you should simply state "thou shall do this or not do this". Don't write a 10 page paragraph explaining why this standard exists and who approved it, blah blah blah, etc...
Include forward thinking into these standards, such as;
where do you want to be in a year (this is part of the how are you going to get there)
how can you gain consistancies to set yourself up for possible automation in the future
Then make sure that you have training for your users so they understand what the standards are and then hold them accountable for their work. Cad standards almost always fail (in a multi user environment) when no one is held responsible for their own work.