* Musicnotes.com: You can purchase the piano sheet music for "River Flows in You" from Musicnotes.com for $4.99. This includes the sheet music for the piano solo version, as well as a chord chart for guitar.
* Sheet Music Direct: You can also purchase the piano sheet music for "River Flows in You" from Sheet Music Direct for $4.99. This includes the sheet music for the piano solo version, as well as a chord chart for guitar.
* Amazon: You can also find the piano sheet music for "River Flows in You" on Amazon. The prices vary, but you can usually find it for around $5-$10.
* Yiruma's official website: You can also purchase the piano sheet music for "River Flows in You" from Yiruma's official website. The price is 10,000 Korean Won (about $8.50).
Once you have purchased the sheet music, you can download it and print it out so you can start playing it on the piano.