As far as I saw there wasn't official reply whether ingots are returned or not. That being said, 100ingot pack is the only semi viable option, you get a total of 30 coupons, 6 lv1 cave key runes, 1.8 seal scroll and 1.2 charm pack. Which is roughly 30cp + 48 (6x8cp per key) + 100cp (2 seals with good discounts) and 100cp (charm pack with discount) so a total of 278cp at least, depending how you look at the value of charm and seals. All items are viable and useful and it gives BETTER overall value than 10x "try your luck" and similar to 10x additional SS convoy (you dont lose on 1.5m gold).