Ill just say that they are illegal, but totally allowed. Theyre for floral decoration, and you can find them on the web, on various sites, for various prices. Do a Google search for papaver somniferum and Im sure youll find them.
I think you might be able to, but Ive heard theyre often treated with nasty chemicals, and its a gamble. Itll also probably be a lot more expensive. Any poppy pods used for decoration will be somniferum (Im pretty sure) so try your luck. you can always get some seeds and plant a garden.
Internet is the way to go. A lot of places are very good about fast shipping, so you wouldn't have to wait long. And I don't think you can find them cheaper anywhere else besides the net. gl.