Best deal for hitting Phnom Penh's essential historical sites without getting ripped off. Start your negotiations at guesthouses along Street 130 in Boeung Keng Kang area - these drivers are vetted and reliable, unlike the random guys hanging around S-21 or Royal Palace who'll quote tourist prices then disappear with your deposit.

Full day circuit covering Choeung Ek Genocidal Center (Killing Fields), Tuol Sleng Genocide Museum (S-21 prison), Royal Palace complex, and Silver Pagoda should cost $12-15 USD including waiting time and fuel. Get their WhatsApp number and agree on specific pickup times - usually 8am start, 2-hour stop at Killing Fields, 1.5 hours at Tuol Sleng, lunch break, then afternoon at Royal Palace.

These sites require emotional processing time, so avoid those $25 hop-on group tours that rush you through Cambodia's tragic history in 30-minute chunks. Your driver will likely suggest good Korean restaurants for lunch (try Grill House BBQ on Street 63) and knows which entrances have shorter queues.

Unlike Bangkok or Siem Reap tourist traps, Phnom Penh prices are still reasonable if you negotiate away from major attractions. Just remember - this isn't a fun sightseeing day, it's confronting genocide history. Budget emotional energy, not just money.