ChatGPT Plus is listed at $20, but the actual price can vary between about $13...

https://mill-wiki.win/index.php/ChatGPT_Plus_File_Upload_Limit_Per_Message:_Is_It_10_Files%3F

ChatGPT Plus is listed at $20, but the actual price can vary between about $13 and $27 depending on where you subscribe. This happens because of extra costs like VAT or GST taxes and app store fees from Apple or Google