How much does the FAA private pilot's license checkride cost?
There's no standard fee for the checkride because each Designated Pilot Examiner (DPE) is free to set his or her own price. I've seen numbers for a private checkride in the \$400-600 range depending on the location, but your instructor should know the local examiners and what they charge. Or just ask the DPE directly, of course. Bear in mind that you might have to pay extra if you have specific requirements like needing a checkride at short notice, on an awkward date, or at a particular location.

This question might be useful too, and see this one for the (unusual) option of using an FAA examiner instead of a DPE.