Yep, I know, it's old.

My EOS 3 side door has become sticky due to the material aging and the climate I'm in. Does anyone know of a good source other than eBay (or Canon) for replacement parts?

Why not Canon?

The door or a spongy seal. Thise seem to change back into petroleum over time. You can buy replacement material for it.

Can be Canon - I was just looking for other possibly cheaper sources.

I presume you are referring to the doors seals getting sticky. The seals that used to look like thin strips of foam. If that is the case the material can be carefully removed and the seals replaced. The best source for those is indeed Ebay, generally less then $10 for a full set of seals for the camera. If you need the actual door www.procamerarepair.com in San Deigo is a great source.

Dave

Sorry - not the seal, the actual surface of the side door that open to press the battery button, clear button, etc.