Hai~... I don't know if, for the new quest, you find the birds or buy them... because some of those prices are a bit high... Thanks!
[img align=center]http://vignette1.wikia.nocookie.net/adventuretimewithfinnandjake/images/8/86/S4_e25_Ice_King_playing_drums.png/revision/latest?cb=20130913175838[/img] <--- Me.
You don't buy them, the birdies appear in your inventory for free. And Rosemary gives you a free book on birds, which also appears in your inventory.
find them! Buy them only if you want to cuz Rosemary doesnt.
There are two kinds or birds. Ones like which you'd find in the place in its name. I had to find that one yesterday and it popped up at the Snowtapult in the Arctic Frost.
Ones like can be found in places like your inventory, the forums, and other pages that aren't associated with a particular place. The bird I had to find today was like this and it popped up on the Bird Watching page itself. [edit] You only get during your first quest to find a bird.

Thanks! :)
[img align=center]http://vignette1.wikia.nocookie.net/adventuretimewithfinnandjake/images/8/86/S4_e25_Ice_King_playing_drums.png/revision/latest?cb=20130913175838[/img] <--- Me.