Just curious on what you will do.

Now that I know you're talking about retics, look at Boamaster cages, too. They are built for big snakes. They are in the kingsnake.com classifieds alot, under caging.

And I forgot Habitat Systems cages. They supply cages for retics.

And of course, when you're talking about the expense of large cages, there is always the do-it-yourself route. Nice thing about retics, tolerances aren't important. A 1/4" gap in the doors won't result in an escape lol.