ECommerce backend build to digital music strore

Looking for someone with knowledge of both SoundCloud API and PayPal APIs to provide backend eCommerce solution for music artist store. Our store pulls music in from artists Soundcloud accounts offering it for sale on web and within a web app on smartphones. The store uses Soundcloud player both in a web app and on the web. We need to allow customers to buy track, add to cart, checkout and send email notification to download MP3.

Looking for someone who has experience in eCommerce, knows APIs as mentioned and can follow direction and get this built quickly