actually the most expensive thing is going to be the printbed.
A sheet of aluminium (alu-mi-num for americans) 2 metres by 40cm by, I dunno 6mm ? Is not only going to be interesting to buy, but it needs to be perfectly flat.
Might be easier to use glass. Would be cheaper and possibly flatter. Mirrors are often used as print beds. Maybe salvage something from an old wardrobe.
Then there's the issue of heating it.
You could go for an unheated bed, but all filaments stick far more reliably to a heated one - plus once the bed has cooled it's generally much easier to remove the print.

There are reasons you don't see many printers that size.