I was talking to a friend about taking a class on Lynda.com, and they told me that I could get a free trial of the site. I thought it worked that you bought a class individually, but it doesn't sound that way...is this the case?
Right there on the signup page, where you can choose either "Standard" or "Premium" and get a 10-day free trial, it also says:
What happens after the free trial period?
You'll automatically be charged your plan's rate on the 19th of every month unless you decide to cancel your account.
So, yes, it's a subscription model.
Also, from the FAQ page:
As a Lynda.com member, do I have access to everything?
Yes. Lynda.com members can watch each and every course in the library. Exercise files are available to monthly premium or annual premium members.
So, no, you can't purchase individual classes.
Fortunately, you may be affiliated with an organization that already has a subscription. For instance, my local public library has a subscription and I can view Lynda.com videos with just my library card.