I got mine at Lowes, actually got everything at lowes. You could even go to home depot or any other home improvement store. If I remember correctly mine cost $18. Measure your current door and if it is a standard size they will have one there that matches. You may have to chisel away part of the door for the hinges to attach also. It is really easy to do though, I did it in an 1.5 hours maybe 2. But you can find the vent faces and everything. I used 1x2's to make the shelf.