I've always sourced replacement seals at my local bearing shop. Just take the old seals with you and when they tell you the 10mm seals are no longer available tell them to look harder! All the seals can be bought easily but some require the bearing shops to buy them in.
There's a thread I wrote a couple of months back about fitting crankshaft seal retainers. The 2C racing people put me onto this and we've had one bike spit its seals out so it's a worthwhile fix to apply if you are rebuilding the bike anyhow.