.. In 1799, it would cost so much to mail a letter-- I don't know exactly, something like $10 or $20 to mail a letter at today's rate-- and it would take a long time get there.

在1799年，寄封信需要花费-,我也不清楚具体的数字,大概相当于现在的10到20块钱-,而且还要花很久才能送达。

耶鲁公开课 - 金融市场课程节选

Most people wouldn't ever mail a letter or get a letter--too expensive, not to count only the paper and everything was expensive.

大多数人可能从未寄过信,或是收过信，因为太贵了，不单单是纸贵,什么东西都贵。

耶鲁公开课 - 金融市场课程节选