Over the last few months I've become intimately familiar with the intricacies of the visa process for various SE Asian countries. I have to give the Cambodian government credit for the most pleasant visa experience I've had to date with their e-visa program. Their user interface was straightforward, allowing submission of multiple requests, they accepted PayPal (believe it or not), and they offered assistance with digital photo optimization if needed. We received our visas the following morning via email. The cost was $5 more than standing in line at the airport, but IMHO it seems well worth it.