Copying transparencies isn't that hard providing you have a good macro lens! The ready made slide duplicators generally aren't as good quality as a good lens (I had one once). Providing you have the macro lens, it's easy! First of all, you need to measure the distance from your lens to the slide, when the image covers the maximum area in focus - with my Tamron SP90, it's about 8 inches. Then you need a cardboard tube (to cut out the light) roughly that length but must be cut square at each end. Tape one end onto your lens casing (hopefully it should fit just inside the lens casing but without touching the glass - that helps to keep it straight). Find an old slide mount, line it up and tape it onto the other end, that makes it easy to line up each slide and tape them onto it.
With my SP90, I have no auto exposure, but in sunlight, f11 and bracket between 1/10 and 1/120 second depending on density - you don't have to worry about camera shake as your 'tube' is tightly taped rigid. Focus by aiming near the sun - you get a clear view of the grain to focus on, then aim at a white surface away from the sun to expose the shots. It sounds like a total cheap bodge, but it's far better quality than any slide duplicators I've used.
The advantage of bracketing is that you can combine under and over exposed images to compensate for over contrasty slides. Here is one I've just done!