Updated: I had a couple of websites for free yoga, but they are no longer useable.
Subscription services (monthly) that are low cost compared to Paris yoga classes and have free trial periods (as of last check):
Has an almost overwhelming selection of well curated well filmed classes in all genres and styles. I've taken classes with a few of these teachers in real life, and they're quite good. Jason Crandell is one of my favorites.
Also has a good selection of well filmed classes. I've taken many a classes with Pete Guinosso in San Francisco in real life, and he has a few here that are very good. I also saw a press release that they were now offering prenatal/postnatal classes too. And it looks like Yoga Journal has snatched them up recently. They do have a few very short free classes (5 minutes).
I've never taken a full class with Aiofe, but she's a fantastic spark of a woman, and a kick ass yogi. And I recognize quite a few of the names of the teachers, so let me know if you enjoy it.
This website is pretty geeky, but they have a good selection of all different kinds of yoga for all different kinds of people.