I started by doing a rebuild on a cheapy BX Estate that has now turned into my offspring suddenly acknowledging that the old boy isn't all 'iss and wind and can actually repaint and restore used and abused cars, so as a result the line is getting longer all waiting for repaints, dents to be knocked and rust to be removed, but in the process of doing a Mitsubishi, I have discovered they also use a similar type of stuff in their bumpers and enquiries in the trade have revealed it's not as rare a commodity as we might think.
Just go looking for any (usually) small one man operation who has things like "Stripes and Graphics" or "Pinstriping" or similar in his type of work description and you'll find they have it in bloody great rolls. Just measure and advise and they'll chop it off in a length and at a lot less than the dealers will charge.
The stuff for the Lancer is about 4mm wide by around 3mm deep and is apparently quite common and not expensive.
I'll be getting a few metres next week to sort this Jappo out. Basically anyone who deals in dressing up "rice boxes" or "Chavs" cars should be able to supply.
Alan S
By the time you're old enough to know it all, you can't remember why you were learning.
heard of a BX!! when I rang in it didnt instill me with much confidence. 
Will keep a eye out, or be brave and ring the main delaer and try and explain what a "BX" is too them!