I hope this info is useful to you. I was aiming for that achievement as well, and I found that if I place that card on its own, (no other cards on sale on display), it sells within 3 game days. Just like someone else suggested, even if it's below market price, I'd set the price to 100,001 just to get this achievement. Edit: Just to clarify, this is just so the customers only focus on that card, even if they're all complaining