Hi Livia! Yes, Pullman bus goes to Isla Negra on the Casablanca line. This is considered a regional bus and they do not sell tickets online. The buses are very frequent – one leaves probably every 15-30 minutes. You can go to the Pajaritos bus terminal (Santiago metro Line 1 – red line) and buy your ticket there for the next available departure. You could also go to the Terminal Alameda (Santiago metro Line 1 – Universidad de Santiago stop), but Pajaritos station is brand new and easier to get around. We paid $5000CLP from Isla Negra to Santiago in July 2015. Hope this helps!
Hey Livia, you can also try PasajeBus.com – looks like they have daily service to Isla Negra. PasajeBus.com is a very popular site to sell tickets inside Chile and Argentina. I was recommended this platform by a friend during my last visit to Chile and Argentina.
Hope you find this useful, enjoy your trip!
That's cool – thanks for sharing! It's nice to have more options than just Pullman. I still encourage people to check at the bus terminal as not all schedules are available online, and you have a lot more flexibility than it may appear if you only check this site.