I buy the precooked (smoked, honey glazed, oven baked, etc.) turkey or ham in the meat department when they are on sale. Then I bring them to the butcher department or the deli department (You may have to purchase it first, just bring them the receipt.) Have them use their big slicers to slice the meat into thin sandwich slices. It saves me a lot of time and it is far cheaper than buying the sliced meat from the deli. You can also divide it up into smaller bags and freeze them for later.
This is a good idea. We happen to have a small compact slicer machine so we can do the slicing ourselves. I bought a package of smoked Jennie O turkey breast and we sliced up.