There is no problems getting a visa in cambodia at any port of entry ...yes sometimes border crossings will price in baht or ask a couple of dollars more but this doesnt happen in airport and is very rare persobally used thai border at koh kong numeroua times and never had problem. If you are endinf up phuket there is now as of this year direct flight on air asia hkt to rep so you can fly into siem reap and have no problems tourist visa is 30usd on arrival . Angkor wat is now managed bu goverment not a third party and entrance prices have now increased 38usd for 1 day 60 for 3 and there is many interesting temples around angkor wot. If your travelling around camboida with kids would recommend just hiring a private taxi a lexus 4x4 for 4/5hr journey should be around 50usd .