With my A1200, I use a PCMCIA CF adapter. I'm pretty sure the 600 has a PCMCIA slot in it too. There's some driver trickery you need to do though, and the only way to get the drivers on the 600 would be to either:
1. Get a USB to IDE adapter, and mount the HDD from the Amiga in WinUAE so you can access it, and make a virtual folder on your PC to transfer files to the Amiga HDD. Workbench, CF drivers, etc.
2. Get someone (like me) to put the drivers on a floppy disk and send them down to you.
Though, Swivel's auction is really neat. That'd probably be the best bet.
Amiga 4000: Apollo Turbo 040, 128MB Fast, 40gb HDD, CD-ROM (needs internet)
C64: 1541U-II, MixSID, WiFi, LumaFix64
ZX Spec, A1200, CD32, MacPlus/SE, A500, BBC Turbo Master (NASA), 2600, Acorn 4000, VIC-20, IBM 5155, GameBoy