Our yard is fenced in so Leo and the cats have free range to come and go as they please from the house to the outdoors. For the cats alone I could have purchased a small door, but Leo is a big boy. I also wanted something that could be locked if I needed to keep him inside or outside for some reason. My final must have was a door that would close securely after the pets entered/exited so we were not losing heat or cold out of it.
I found numerous options but most were $75-$100 and up. The pet door was a necessity. The budget minded me was not happy to spend so much money though. I continued to shop online and read reviews. Some that offered a secure closure would have been difficult for the cats push through. Others that were easy enough for the cats would not have provided a secure closure.
I ended up choosing one made by BarksBar. It was very affordable - priced at $36.99 at the time I purchased it. The vinyl flap closes securely but is easy enough for the cats to push open. The self-locking slide panel is easy to operate. The door has a nice look to it as well.
Time will tell how well it holds up. For the time being I could not be happier with the price and the door.