Garden birdhouses have been popular elements of backyard landscaping for decades. They are available in a staggering variety of sizes and designs, and for the most part, are relatively inexpensive to purchase. Furthermore, they can be found through just about any home and garden center in the country, as well as through dozens of online vendors.
There are very few steadfast rules when it comes to designing garden birdhouses. They can be as simple as a reconstituted soda bottle or as elaborate as a handmade reproduction of a Victorian-era mansion. The only real requirements are that the entrance is appropriate for the species of bird you are trying to attract and that it is placed in an area that is inaccessible to potential predators.
If you are in the market for garden birdhouses, the best place to start is often your local home or garden center. These businesses often carry several varieties on hand, and can also special order items that they might not have in stock. Of course, today there is always the option of looking to the Internet, and there are many online businesses that carry birdhouses as well.