Ah - I kinda miss-interpreted what this was going to be.
*cough*
How about designing an enclosure with 20 laptop dimm slots, ddr will do, that would allow 20x2g slots
Allowing the user to insert as many as they choose.
Make a ddr2 one, ddr3 if u like. Micro sd cards would be more sensible as u can get 8g the size of ur thumbnail.
The effect would be a larger unit size than an SSD - obviously (unless u went the micro sd route) - but it would be a damn site easier to purchase. And the speed would be as-good if not better.