I look at Petsmart.com for gates for Roxy since we have stairs in our house but have not been able to find any for less than $35. I've got a wooden gate with plastic mesh for $20, but that's not a walkthrough one. However, even though it is $45, I've found the Evenflo Wide Spaces Swing Gate works well. It fits spaces up to 42'' to 60'' feet wide.
Hope this helps!!