Yeah, I came across a place like this when I was looking to buy Maya 4.5 for the Mac. I emailed them, asking if they had 3.5 or was it 4.5, because their price was really, really low, and I figured it was just a used copy of 3.5. They responded by saying they had both, and that they had Complete and Unlimited for the Mac. I was a little shocked, so I checked Alias|Wavefront's site... and no Unlimited.
Needless to say, I didn't feel like loosing a few hundred on a chance, so I bought Maya from Alias. It took a little over a month to get it, but I've had fun with it ever since. 
I can't believe I actually considered buying Maya that way. I am still relatively new to this internet stuff, so I didn't figure there could be illegal practices like this happening so openly. Now I know. And knowing is half the battle. Gi Joe and all... LOL
My advice, is save yourself the chance from future backlash, and buy Maya from an authorized reseller. 