If you dont want to break the bank and are able to do some simple mods.
Here is a very solid steel body drag knife capable of cutting 1/8 inch card board, magnet sheets and even thin aluminum.
Price check online.. for Cricut Deep cut Blade Housing I paid 28.00 for it.
I had to make a sleeve for the body, and grind off one rib.
Amazing little knife...If you need more info PM me...