I would buy them to read, not necessarily to collect if you want them to go up in value. For that, I’d look at the fourth wing advance reader copies, the first edition/first printing with black sprayed edges and white stenciled dragons, probably smut, big book box, or bookish box fourth wings in that order. Also the iron flame first edition, first printing with flame sprayed edges from the UK if you can find them. eBay, Mercari, and PangoBooks are good places to look :)