This folding conveyance cost me 30 pounds and a tube ride to the West End and back.
It was rusty.
I scrubbed the chrome with aluminium foil to lift off the rust, oiled everything and replaced the handlebars / seat.
An illuminated sign made from a wash basket and reading lamp later and...
The light-up box cost about 5 pounds in materials from Poundland. Total for the project is about 50 pounds including the bike, new handlebars, seat, and sign materials.
The sign box slides off of the back tray easily, so that it can be switched out with different ads.