Doors!

It has come to the stage where I have to replace the doors on my 110 300tdi csw. Where the bottom half meets the top half has gone! I have three options. Standard doors and flood them with paint on the inside then waxoyl. Galv doors which seem impossible to get or grp doors which seem untested?? All options are expensive unfortunately but better to do the job right! Or is there an option of sending the doors to be fixed.(. There is a 4" gap!).
Thank you for your help