Reciprocity means your country charges theirs, so theirs charges you. The result: identical visas at wildly different prices.
Turkey is the textbook case. Mexicans pay $20, Americans about $50, Canadians nearly $70, for the same e-visa on the same website.
India's 5-year e-tourist visa costs most nationalities $80. Americans pay $160. The 30-day version drops to $10 in the April to June off-season and $25 the rest of the year.
Sources: U.S. State Department, IATA Travel Centre
This is why "how much is the visa" has no single answer. The fee follows the passport, not the destination. Budget by nationality, and when traveling as a mixed-nationality family, price each passport separately. The total is often a surprise, and it is always non-refundable, so get the number right before anyone pays.