score:2
You can purchase a visa on arrival by paying USD or Sri Lankan rupees.
The ETA website does work, despite not looking very slick.
I've tried out both methods as I typed in my passport number incorrectly to the ETA website. Immigration did not accept by online ETA receipt as it didn't match my passport. I was then forced to purchase the ETA on the spot.
Upvote:2
According to this website, citizens of almost any country, with a few exceptions listed on the page, can obtain a visa on arrival for up to 30 days.