"so just offer a price and it's yours! This is a lot easier than auctioning everything so don't be afraid to ask for an item~"

I don't think they really gave a damn, honestly. It seems pretty fair to me. Could they have offered more, sure, but the seller could have listed it for a price they wanted too. It just happens that the didn't really care and were open to anything. Be glad the seller even got more than 1t!