Or just get a decent quality closeup diopter to put on any existing long lens you may have, something like a nikon 5T or 6T.
quote author=Adam Lincoln link=topic=13040.msg230720#msg230720 date=1259318540]My flash won't really be up to the job, as its a sb600.
For really nice results you want two flashes in the ten-to-two position, in fornt of the lens. Macroflashes are basically ways of doing this neatly, a cheaper option would be a SB-600 and a SB-R200 in a home made bracket. Or a cheapo macroflash in manual.