Yea, Yahoo shopping is buggy as hell, the price thing, and the fact that not all their merchants show up.
I tried to email alphacraze for a list of their inventory, but they never responded. IT seems though that most of the manga im interested in, they sell. Basically, you just gotta do a search in the Books catagory, even if the price range says higher than $4.79, check it, a lot of the times, their 4.79 prices are in the section of "$6.00+").
Im gonna order another 15 books from them in a few days (after i see whether they get the new Fullmetal Alchemist this week or not) I already made a cart just to see how much the shipping would be, and it said $1.99, which still is pretty damn good for 15 books.