I found this list on Broke Girls Guide. Below is a guide to cheap (or free!) workouts around LA:
Annenberg Community Beach House – If you don’t feel like sneaking into a hotel pool or being hit on by out-of-towners while you tan, pay just $10/day on weekends for a swim.
Beach Volleyball Santa Monica, etc. – Grab a group and set up shop at one of the many free beach volleyball courts around town.
Bryan Kest’s Power Yoga – Keeping in mind that yoga-by-donation does not mean free, this is still a great deal. If you don’t live west, you can livestream classes (also by donation).
Escondido Falls – Is there a less painful workout in existence than a Malibu hike ending in a waterfall? Trailhead is at PCH and East Winding Way.
Lululemon Athletica – The Yoga and/or Pilates classes offered on Sundays are so good you won’t believe they’re free. Check individual store websites for details.
Runyon Canyon – If you can stand the overwhelming stench of dog pee, this is a great hike. Runyon also offers yoga-by-donation.
Santa Monica Stairs – The people hiking them are in such great shape you’ll be motivated to keep up so as not to cause a traffic jam.
Santa Monica Swim Center – This westside pool is only $3.25 per visit for Santa Monica residents, or $6.50 for non-residents. It’s a little more low key than Annenberg.
Temescal Gateway Park – Hands down the best hike in town. Breathtaking views of the entire city on a clear day, and no dog pee. Also, there aren’t as many people on cell phones and/or gossiping loudly as in Runyon.
Two-for-One Tuesdays at Sunset Ranch Hollywood – Horseback riding here will normally run you $30/hour, but on Tuesdays you can split the cost with a friend and get an hour for $15/each.
Your Neighborhood Studio – Sign up for their newsletter for tons of free class offerings.