I am wanting to put a wood stove insert into my existing Zero Clearance fireplace (not masonary). My current firebox is not insert rated and would be unsafe and against code to put an insert in it. I have looked all over the Internet and cannot find a site that sells these fireboxes anywhere. I just want to buy a new firebox which will accept a stove insert. Can you recommend a site(s). I know they sell whole zero clearance/stoves together such as napoleon brand. But these units cost around $4000 and is out of budget. Thanks for the help!