Hey Anthony
I ordered it from Solitare Spare Parts up at Mile End.
From memory it was about $9.50 and had to come from Sydney.
I did it over the phone and picked it up a week later.

Not too hard to fix but you just need to manoeuvre a screwdriver into the lock so you can release it, and put the new part in.
Spray some WD40 or oil of some sort in the mechanism so it lubricates the lock and is easier to open.

Do you think its worth going for coils? or Springs?

Cheers, Nathan