Saying a Price in Quid, says You are in UK, a lot of the Carradice Alternatives will Be Imported .
Carradice is in the Midlands,
RE plastics, It depends on Which One you are considering, LDPE or Styrene/ABS, Poly-Carbonate ,
and carbonfiber filled Nylons, are all plstics, but their performance chacteristics are quite different.
Take a Look At Rixen & Kaul's Klickfix systems, they offer a seatpost adapter
that fits the seat post , to fit a handle bar bag as it is, on the back ,
if it uses Klick fix ( or Ortlieb) mounting hardware.
Then you pop off the bag when you stop, lock up the Bike and take it with You, .. into the Pub.. etc.
Last edited by fietsbob; 06-05-13 at 10:45 AM.