I called in to my LBS yesterday to pick up an aircan service kit for my fox rear shock. They denied the existence of such parts, and advised sending the whole shock for service (££££).
Hey ho says I, stripped my shock and headed to my local seal house, who kindly supplied the following:
1x 215Q (Air sleeve quad ring) £1
2x 215 PTFE backups 60p ea
1x 218Q (Air piston quad ring) 80p
2x 218 PTFE backups 80p ea
1x 126N70 Air sleeve seat o-ring 10p
1x 028N70 Air chamber o-ring 8p
1x 1-1/16x1.335x0.102 AN Wiper £1.30
and the DU bushes, 1/2x19/32x1/2 x2, 80p ea.
Those are all standard industrial seal part numbers, so any good seal/bearing shop should be able to help you out.
I realise that the all up cost is not far away from the Fox kit from Mojo et.al., but this stuff was just around the corner, and those numbers might help if you are in a jam.