ChatGPT Plus is listed at $20, but the actual price can range from $13 to $27...

https://www.active-bookmarks.win/chatgpt-plus-has-a-list-price-of-20-but-the-actual-amount-you-pay-often

ChatGPT Plus is listed at $20, but the actual price can range from $13 to $27 depending on where and how you subscribe. Differences come from taxes like VAT or GST and extra charges from app stores