The highest quality sampler made for a basic "wedgie" Amiga was the Aura, which could sample in 12-bit, but required a PCMCIA slot (and another port on the back). I think it worked with both A600 or A1200.
IIRC, there was also the Clarity, which was 16 bit, never used it myself, though. It had a MIDI interface too, IIRC.
I had the GVP DSS8 8bit parallel port thingy, which I won't recommend, unless you want low quality, crunchy sound (but hey, it was cheap).
I'd go for a complete sound card solution, if of course they have inputs at all, I can't say that I know much about Amiga-specific sound cards.
But even an SB 128 would be a better solution than the old 8bit samplers (but only if you have PCI slots, of course).
