I don't know if this helps at all. TRU has the INTEC mem expansion pak (8mb, same size as a Sony card) for $3 or so. This is the one in the thinner blister pack that doesn't require a CD. I bought one and it seems to work. You'll need a REAL Sony PS2 memory card to plug into it but after that you can switch between the Sony card and the expansion pak memory.
* I only used it to copy and archive old sports saves so I don't have experience saving/reading it directly from a game but so far it seems to work OK.
If anyone else has had experience with this item, please feel free to post your experience.