If you see postage cost of $25 or even $40, the seller is most likely not accustomed to selling cards overseas and uses whatever is default on eBay, which could be the quote for parcel post. The easiest thing to do is ask, the worst outcome is rejection, you move on to the next seller. Some sellers are willing to work with the buyer to achieve a cost effective delivery, but USPS has become more strict with their mail classification, a lot of what used to be Large Letters are not Packages, which is why it is costing $7 rather than $2 back then. And their postal system sucks, they have to fill in forms at the counter, so it is hard to get away with just buying stamps and sticking on whatever you believe it should cost LOL.