Hi I would firstly get a price from the Caterpillar supplier. They can often be competitive. Not being from your area i couldn't suggest an after market supplier.
Regards Gordon.
You can look for an after market supplier of tracks, bucket teeth, etc.
I used to get good prices and service from a company that handled cutting edges, and bits made by the Bucyrus-Erie Company. I had an old LeTourneau pull pan that I couldn't get cutting edges for...I measured up what I needed and they ordered them for me. They had to make them but the cost was still very resonable. Took about 3 weeks if I remember right. I bought a lot of cutting edges and bits that they had in stock but the Let was just to old and out of date.