FYI, did a Visa Exempt Border Bounce in Chong Chom / O'Smach yesterday. VOA for Cambodia is 1.3k baht, USD not accepted (I really try, bills were very clean)). Then there a 300 baht bribe after filing arrival-departure card (10 usd can do for this one). So overall it's 1.6k baht to Bounce in-out. It's much quicker then Nong Khai border ofc because it's empty and other side is like 30s walk from each other. Can do the whole thing in 20 min depending on how fast you can write. Nothing else to know it's really easy process.