I will answer the questions here because i'm here actively selling different giftcards.
1. You can opt any of the top escrow services here in bitcointalk. Here is the link.
https://bitcointalk.org/index.php?topic=855778.0 , Hold the amount until the item ships.
2. Amazon sometimes automatically hold the account for few days if you are redeeming large amount of giftcard at a time and making the order even if there isn't any issue with the card. But if you are account is old enough then that won't be an issue. This applicable only to new accounts without any or less order history. Another case would be the giftcard has been reversed due to some reason ( carded gc's, frauds etc..). This time they will cancel the order you have been made and block the account right away. By contacting them they might enable the account but still the gc you can't use it again. They will ask you to contact the source to get the refund. In this case you will be in loss.
3. Paxful is a mix up of everything. Even with high trusted users you might get gc's obtained illegally. There you can't hold the fund until item ships..You have to release once you redeem. So that's risky due to the reasons mentioned in point 2.
4. You can use purse.io for purchasing items with a discount. Raise.com is an another option for discounted cards, if something happens with the cards they will offer a refund and bitify is also a good option.
or else i can offer the card when i have in stock with the hold period of 12 hrs.
If you have any more questions then let me know.