You don't say in particular what you can't find. Are you looking for shoes, cylinders, hoses? In most cases you can go back to your jobber with your old shoes and have him send them back to the remanufacturer for new shoes (linings) to be installed on your cores. Kits are available to repair your wheel cylinders. Hoses can be compared and fitted to those a jobber has in stock, plus or minus an inch or a bend.
Try using someone other then a "chain" auto parts store, a good independent will help you out over the long run.