indeed they are very hard to come by sadly, I am well aware of their scarcity
we have been aware of those 7448 SBCs for a good year or 2 now (its where the 7448 used in the iMac above originated from ) with confirmation that indeed we can make 7448s work @dosdude1 struck a deal with the ebay seller and he bought 6 of the units to pillage for 7448s.
indeed we spoke about the ebay listing
i also spoke to dosdude about the ones on alibaba but not sure how to come by them from there .. they have 1.6ghz and 1.7ghz ones for like 5.00/unit .. not sure how legit or easy it is to obtain from there