Heard of Cardsphere? Best website to sell cards, never got scammed and I've sent over a thousand envelopes. They remove money from the buyer account before you send it, if the buyer or seller open a dispute, they manually check and track case.

-Bubbled mailed doesn't change much, I had instance where they literally folded it. -Top loader isn't the best option IMO, if it get processed in machineries it get more damaged, I have pictures of instance it happened to me and you can clearly see why this isn't the right solution. ( I also have YouTube video explaining this and Rudy's from Alpha Investment backing this ) -Tracking isn't the perfect solution either, had many instances where my mail carrier simply put the envelope in the wrong letter box and marked "Delivered", luckily my neighborhood are nice people. -Writing "Do Not Bend" on envelope actually DO something, people are not aware of it, ask your mail provider, they are supposed to sort it differently.

Feel free to ask me questions, I'm pretty confident with the amount of cards I've sent.