The official Cambodian eVisa website at http://www.mfaic.gov.kh/evisa/ now charges 10 USD extra if the travel date is the next day - or maybe anything sooner than the official 3 days processing, didn't check that. So it's 20 USD for the visa, 5 USD eVisa processing fee, and 10 USD express service (if applicable).

The website gives a nice warning about the surcharge when choosing the estimated arrival date.

They used to issue the eVisa within a view hours without an additional surcharge.

Btw, the website is in a pretty lousy state at the moment - tied to sign up as a 'frequent eVisa user' but couldn't complete the process due to 404 NOT FOUND errors.

The eVisa application itself worked, but only with one of the ePayment providers.

I guess it's a temporary issue and they will sort it out.

Moved to visas for other countries.

Just another reason not to use it.