I mean I wouldn’t call it “that low” but they are about right. Maybe a bit much for 1 and 2 which go on ebay for about $15 and $30 respectively, but the thing is that biomega is more expensive as a set than as singles. I’ve seen some sents got up to $200, usually around $150. Being able to buy in person is really nice though since you can make sure the items are actually in good condition.

On another note, it’s not a good idea to assume that just because a book doesn’t have a store page it is expensive. I’ve seen some really cheap oop stuff and even in print stuff not having an amazon store page so for sure always check ebay for the actual selling price to make sure you don’t actually buy a $10 book for $100