There are basically 3 options for macro : -
1) Close up Adaptors
This is the cheapest option. They go on the front of your lens like filters. As this is extra glass - and usually very poor quality at that - it can cause CA problems. I've got a set. Cost £15 and I was ripped off
This is taken with a close up adaptor installed. Notice the blue and red speculy bits at the edges. This is the CA caused by the cua.
2) Extension Rings
I've not tried these and have heard various pros/cons about this sort of thing. They go between the body and the lens. They don't contain any glass so any IQ issues should be down to your lens itself.
I've heard peeps say that they can't meter with extension rings. Dunno if that's true or not.
Expect to pay from £70 - £100 for the kenko set of 3 tubes.
3) Macro/Micro Lens.
This is obviously the best option IQ wise but is the most expensive. The main thing rha should concern you terms of which lens to get would be to make sure it's an AF-S model.
hth.