I use to use Macmall all the time years ago. They always were reputable to me. I can not say how they are now, since after them I found Fry's then moved on to online only purchases.
The last computer I purchased from them was a Performa 6400/180, then later on upgrades for it like a G3 250mhz accelerator, and an ATI Rage video card .
We ordered an ipod nano from macmall along with the case and fm transmitter that were free after rebate. The product came as expected and the rebates arrived really fast. They're an excellent company.