We're trying this year to attract a nesting pair of bluebirds to our backyard. I visited several retail outlets finding prices from $19.99 to $59.99. After an internet search I found free plans from the US Department of Agriculture and with scrap lumber made my own.
All painted and ready to mount to the post. Now all I have to do is dig and cement the 4x4 post into the garden with a post hole shovel!