The few parts that are needed, you can get from every better store, which sells electronic components.
Except the 74LS244 chips. Not all do have them in the narrow soic package (which is needed here). (So you have to look out for the 74LS244NSR chips)
E.g. I order my stuff always from digikey. But as said, I'm a professional anyway, so I don't know the best places to buy for hobby people...
Maybe someone can help here.