Depends on which version we're talking about.
This is the Photoshop Touch (for tablet) forum, where we discuss Photoshop Touch. It's $9.99 USD in my country off of Google Play or the App Store.
If you're inquiring about Photoshop CC, it's also $9.99 USD/month via subscription.
as an addition: here you will find all Adobe's products. By clicking into "Buy" you will see the Prices
>>> http://www.adobe.com/downloads.html?promoid=JZEFS use "Join | Start for free | Learn more" or "Buy | Try | Learn more"
... ah I see, you could use spanish written websites too:
and (change language at the bottom of) https://creative.adobe.com/products >>> language/Idioma