Yoga is probably the most logical enhancement to a successful climbing career, particularly if you consider the long-term effect. Short-term simple cardio and peak performance training might bring you more immediate success and improvements. The effects of Yoga (Wiki) on your climbing are more subtle. While classical training techniques (see here: Lizenz zum Klettern (German)), focus on the generation of strenghts and blocking powers and uses the stretching techniques only to counterbalance the effects of those trainings, Yoga in my view takes a different approach, independent of the actual climbing training.
Some effects of traditional climbing training can be witnessed in your climbing gym: round or hunched shoulders due to an extremely strong muscle basis in the front and limited counterbalance in the back. The effect of climbing if left unbalanced can be checked by yourself during any climbing session: Just stretch the fingers of your left hand, grab them with the right, bow them back towards your bicepts. Do this e.g. before and after a long traverse. The effect will be impressive and shows how much an unbalanced training might shorten your muscular system.
“Yoga promotes balance, increases core strength, calms your mind, and teaches you how to be in your body”
Heidi Wirtz on http://www.climbing.com/
Excitingly the fact that Heidi states is exactly what promotes a long-term effect: core not external strength and promoting balance. The last point is of key importance and is addressing the point I mentioned above: balance to the focus musculature of climbers. This is also why I would suggest to practise Yoga in parallel to your climbing training, especially if you do not climb every day or less than 2 days a week. Particularly for you this might be helpful.
How to select the right teacher? This is a difficult question. Yoga unlike climbing depends to 120% on the teacher. You cannot rely on suggestions from friends or just looking at a session, you need to test and practice personally. If you do not feel fully convinced by what you feel or see, leave it and check out a new teacher. Yoga depends on the fit of the flows and practices as well as the personal sympathy of the teacher.
In our case this is Soa Fersch from SoaYoga, with exactly the right flows to counteract the effects of climbing training. A Yoga session in a Yoga studio costs between 15€ – 25€, private sessions start from 80€+. All in all a fair price if you add it once a week to your training schedule. After a while you pick up the flows and can practice the simpler ones for yourself. But a teacher at the beginning might help to ensure the correct motions and techniques. So don’t necessary save on that front.