I have had two games on Amazon "sold" for the past four days. They are currently pending until payment clears. What exactly is taking so long? You put in your credit card info and it gets charged. Or you pay with gift card. Does Amazon allow for checks? I am just wondering how in the world payment can take any time to clear, much less four days.
The pend could arise from any reason. Maybe there is a flag on either the buyer or the seller. Or there's an issue with the payment (i.e. credit card flagged for fraud). I would try to be patient and let Amazon do its thing. The worse outcome is for the seller to send the games and it turns out the purchase was fraudulent and the transaction gets reversed while your games are in the mail (and you can't get them back).
Most common cause is actually trying to pay with a credit card that is declining for whatever reason, be it stolen or just not enough credit available. Amazon will automatically keep retrying it, and IIRC, they officially say it can take up to 7 days, but I've heard stories from some where it takes up to 2 weeks.
I've had a sale pend through Amazon for 30 days and it eventually went through. Usually after 4-5 days it goes back into my inventory. It's pretty common unfortunately. Either wrong credit card info (bill zip code, expiration, etc) but I think they send you emails or reminders to try again, so if they try again it resets the clock and if it's wrong again it'll continue to sit.