Hi
There's some scope to achieve what you want with the [cheap] Gotek units.
First, the author of the HxC software has made available a version, similar to that used for the HxC, that runs on a standard Gotek. This may have some limitations, such as requiring all the floppies stored on a drive to be formatted to one capacity, such as all 720k. Details can be found some way down the page of HxC downloads.
Second, there is software for Gotek units available from a company in Germany: at
www.ipcas.com. They sell floppy emulators.
A further point: if you get one of the 1984 Kaypros (or later, such as 4/84, 2x, 10, etc), you can use the KayPlus ROM (2732, 32-pin socket) to allow 720kb drives to be recognised, which would allow a 3.5 inch drive to be used as well as an emulator unit. The TurboROM may allow this as well. Some people have worked around the conversion of the ROM socket to allow this to be done with the 1983 Kaypro machines.
You might also find it worthwhile to investigate the FreHD hard drive emulator, which has been used successfully with Kaypros.
Good luck.
