1. Click on this link, the official web site fot the Cambodian Evisa!
2. Create an account, apply and pay $36 for single entry evisa, valid for 3 months, but 1 months stay, processing time maximum 3 days.
I visited siam reap back in 2014, at that time there was no E-visa, i applied in their embassy in hanoi, and the consular charged me $100 for express sticker visa service! I got it in 15 minutes!
i flew from Hochiminh city to Siam reap, And when i arrived in siam reap airport, they were very strict! First of all the Cambodian immigration officer asked for a tip! So i simply said i dont speak English because i didnt want to give a bribe!
Then got escorted by another immigration officer to the investigation room to check my flight & accommodation! After like half an hour waiting they let me go without paying a bribe!