SD is available in 512 MB now for around $140 and the 1G should be out this year. Cheapest 512 MB compact flash would be around $95 in comparison now, but might be slower. Compact flash has been available in 1G for a while (I have 2 of them) the max cf now is 6G at around $5000

The Panasonic reader is needed to put audio on the SD card to play back in the 7000 or 2600, virtually any reader will do for technics and midi files. The 7000 and 2600 don't use wave files, a 128 card can hold around 45-50 typical songs in audio format high quality, some more if you use the normal compression for keyboard playback.