I am not sure how large of bowls you want to turn, or how experienced a bowl turner you are, or what equipment you have. You can turn bowls out of standard 4/4 lumber by cutting/turning rings and gluing them up similar to a segmented ring. You can use various contrasting wood or veneers between the rings to add different looks. Basically you bandsaw a piece of flat wood to a circle slightly larger than your finished bowls/vase largest outside diameter, glue a sacrificial round wood tenon for the jaws of your chuck to grasp. Then, with tool rest turned across face of wood, make circles for your cutting of the segments. Use a thin parting tool and cut on the circles at about a 15 to 25 degree angle towards the lathe, letting the cut ring fall onto the head stock. You then stop, remove the ring, remount the board, and cut the nest one. (you can leave the ring until you get 2-4 rings before removing). After you have the rings cut, stack them on top of each other with glue and pressure (weight), leave over night. Next day you have a partially formed bowl ready to turn on the inside and outside. This way you do not wast a lot of wood, or spend a lot of time hollowing out the center of a bowl, and get practice with segmented bowl work. You can use this same process with 2 or 3 different colored woods for making interesting contrasted bowls, and, if all the rings are layed out in the same way, you can have enough rings for 2-3 bowls. Just a thought
you can usually find flat cherry or maple at most lumber yards and home improvement stores