One of those like Rick shows that is also adjustable just a bit for width would make it worth the time to do the work. Even at a fixed slice for stuff like bread for Italian meals at about 1 1/2" would be ok, but adjustable would bump it up to making it worth it, to bake yer own bread, talk about cost savings, put "Wonder" out of business, at least as far as your house is concerned. I use Wonder generically, wouldn't eat it on a bet.
Till then what Steve made is perfect. I don't have one for bread, but I do have one for
hasselback potatoes Something I have noticed after cutting a lot of loaves into slices. If you have nothing but a knife in hand, the bread seems to always flatten as you try to cut through. With either of the items used above that doesn't happen.