I have 6 Inkuyo CDs ... great stuff. I also have Inti-Illimani.
Similar sounding, maybe not as pan-flutey: Khenany, Alturas, Echoes of Incas, Rumillajta, Savia Andina, Sukay. I have all these too.
Most of these groups are on the Narada sampler called Andean Legacy. It's a good one to get an idea of whether you like a group enough to buy their CD. I don't know if it's still sold, if not I'm sure it could be found on the second-hand market.
For Inkuyo, Temple of the Sun has tracks that will blow you away (no pun intended) if you like pan flute. They are the best group listed for this sound.