Most of the time, the big conferences specially, come with a section of "why you should attend". Try to put dollar signs on the knowledge you are acquiring if it had to be outsourced: for example, if you had to hire a professional to answer questions about Compensation it would be much more expensive than the conference, probably. What I do, I always write a report with my findings and learnings on the conference. I would encourage you to start with local conferences first, show them the value of your attendance, and escalate gradually to regional and national. Best of luck to you!

We have an informal policy that every employee should be able to attend one off-site conference/ training/ workshop/ etc. per year. The pace of business is accelerating faster than ever before and if you "don't know, what you don't know" the company is exposing itself to considerable risk.

Then rhetorical question I ask is "what is cheaper? sending me to a conference where I can learn about ________ or losing a lawsuit because none of us knew about it?"

If there is any form of on-the-job training, this falls under that umbrella. Tuition/ training/ vocational assistance? I don't need another degree, but I do need to know about legislative changes that affect the company. If certification is required for a job, the company is obligated to fund the CEU training. 

The better qualified everyone is, the more attractive the company becomes as an employer of choice. Word will get out if a company develops its people or treats them as replaceable parts.

Invest in your people, they are the engine that drives a company towards success or failure. 

As a business owner, I encourage employees to think of things like this as a business case.  What is the event, why do you want to attend it, what are all the possible costs (direct and indirect) and what are the benefits?  This will help your manager, owner, or finance have the facts to help support your interest in attending the program.