I have now seen three different instances of people selling letters on etsy. These are not old letters, but more like a "I write awesome creative hand-written mail-arty letters, and if you pay me I'll write one just for you!" kind of thing.
I am not linking them here, because, you know, I try not to be TOO snarky. (I really do.) And hell, part of me says, if somebody pays you for it, more power to you. But from a personal standpoint, I find the idea kind of off-putting. My letters are gifts to the recipient - some don't get too much effort or love put into them, and some get a hell of a lot, but they are all the product of a moment in time, my thoughts and effort for someone else. I can't imagine charging for them. This is not to cheapen the efforts of professional letter-writers who help craft just the right words for someone for a special occasion - again, not my thing, but I can see the market and the business for that. No, the stuff I'm talking about is just an etsy listing for the actual hand-written item, with artsy touches in some kind of a decorated envelope.
I grant you, this is coming from a woman who left a creative career for which she had years of specialized schooling, because she found the whole self-marketing process distasteful. So there's some perspective for you.
We're giving it away for free, people!
But for me... that's totally the point.