Here is one Pegasos for sale:

http://www.ebay.com/itm/Genesi-Pegasos-2-NextGen-Amiga-PPC-Can-run-MorphOS-3-2-Linux-OS-X-MacOS-etc-/261264829208?pt=Desktop_PCs&hash=item3cd498eb18

However, it doesn't seem possible to buy AOS 4.1 for Pegasos anymore. At least not in the Amiga online stores I looked.