Priceless

A Yoga timeline:

900-500 BCE: Yoga Tapas (techniques)

3300–1700 BCE: Yoga Asanas (poses)

200BCE-300CE: Patanjali's Yoga Sutras

1100CE: Gorakshananth (founder of 'Hatha Yoga')

1500CE: Yogi Swatmarama's 'Hatha Yoga Pradipika'

1800CE: Ramakrishna Paramahamsa's Yoga (Bhakti)

1900CE: Sri Krishnamacharya's Yoga (Vinyasa Krama Yoga); Sri Aurobindo's Yoga (Jnana)

1920CE: Mahavatar Babaji's Yoga (Kriya)

1930s: BKS Iyengar's Yoga (Iyengar Yoga); K. Pattabhi Jois's Yoga (Ashtanga Vinyasa Yoga)

1940s: Swami Sivananda's Yoga (Sivananda Yoga)

1950s-60s: freeweights; exercise bikes; Srivtasa Ramaswami's Yoga;
-Indra Devi's Yoga (born: Eugenie Peterson);
-Swami Vishnudevananda's Yoga (the "Flying Guru", ref: Sivananda Yoga);
-Swami Satyananda's Yoga (ref: Sivananda Yoga);
-Swami Satchidananda (ref: Sivananda Yoga);
-Swami Radha's Yoga (Ursula Hellman, ref: Sivananda Yoga)
-Maharishi Mahesh Yogi's Yoga (Transcendental Meditatoin [TM] and the Beatles)

1970s: swimming; interval training;
-TKV Desikachar's Yoga (ref: Vinyasa Krama, 1900CE [his father]);
-Lilias Folan's Yoga ('Lilias, Yoga and You' on PBS);
-Bikram Choudhury's Yoga (Bikram or 'Hot' Yoga);
-Judith Lasater's Yoga

1980s: body building; aerobics; , step aerobics, stairclimbers, resistance machines, martial arts; Yoga. (Workout clothes become fashionable.)

1990s: in-line skates / rollerblades; Nordic Track; Pilates; kickboxing; elliptical cross-trainers; cross-country ski machines; aquatic exercise; Yoga

2000s: cycling / spinning; treadmills; heart rate monitors; dance (Salsa, Ballroom, Pole, Hip Hop); low-carb diets and the 'fitness, nutrition, dieting' combination; Yoga

Some things are not just priceless, they are also timeless.