I'm surprised nobody has mentioned Pro-Line from Constrictors NW.
I looked at them all. The Pro-Line had the best price for the size and uses superior HDPE plastic. It's the best plastic around in my opinion. Nothing sticks to the plastic so it's easy to clean.
My cage was EASY to set up. It looks like this.
I have a step by step setup thread I can link you to.
Ed Lilley's customer service is excellent. He called me when I setting up my cage. He answers e-mails, calls and texts.
I will say AP also has great customer service.
This 4' X 2' X 14" cage came to my door including delivery price for $263. That included my extra 3 sets of perch holders and a lock.
14"s of height is really nice for a boa in a 4 foot cage. You can jump to 18" but I'm seeing good headroom with 14" and perches.