if you have minimal wood working skills you could build one out of wood. you would need
one piece of wood for the back (AKA, book back--where the back of the book rests against) and one piece of wood for the bottom (AKA, the book rest--where the bottom of the book lays against). Your choice on dimensions (you could make it super wide or close to a standard size) and about 1/8 inch thick. you will also need a piece of wood roughly 1/2 inch by 1/2 inch and the width of the book back. a piece of molding works great as it provides ample gluing surface and looks nice. glue the molding onto the book back and then glue the book rest on top of the molding.
two pieces of wood about 1/2 length of the back and 1/2 inch wide and 1/2 high. clamp the two pieces together and drill 4 or 5 holes through both pieces of wood so that each piece of wood has about 4 or 5 holes running from one end to the other. remember to clamp and drill to make sure the holes line up. think adjustable bookshelves. glue the pieces roughly 5/8 inches apart onto the back.
one dowel rod 1/2 inch in diameter and about 1/2 the length of the back. drill a hole through the dowel rod at one end. slide the dowel rod in-between the two glued pieces on the back and find your angle. notice the dowel rod is 1/8 inch narrower....for a reason.
finish using a small can of pre-mixed on the shelf shellac. Make yourself a make French Polish button out of an old t-shirt. FP away. You can tell your friends you French Polished it.
note: if you look at the metal stand in the picture the two pieces of wood and the dowel rod are the equivalent of the back two pieces with the metal rod that attaches to the stand and props it up.
be true to the one you love but have many flings with different guitars