The easiest thing is to tell buyers like this that you set your prices in US dollars and have no control over exchange rates or prices they see in their local currency.
Today a buyer from Canada paying for a $200 (US) gig would pay $265. This changes in accordance with the currency markets and does not include Fiverr $2 service charges.
I have a New Zealand buyer who has accused me of using bait and switch pricing previously. He was of the opinion that if I charge $20 US to my US customers, he should pay $20 NZ. How some peoples minds work is just beyond me.
In either case, just point buyers to the days exchange rate and tell them that you are sorry, but the price they see is the price they pay if they want to work with you.