I'm also not sure which device would be the right one for you as I don't know those things well. The best choice for you I think is to look at eBay as they have The Link 97 there sometimes.
Btw if you have a Windows-computer, you can use those disks inside your pc with a nullmodem-cable connected to the atari. There is a software calles Ghostlink which provides you wth the possibility to use pc-harddisks with your atari. I've done it with a Mega St, with a Mega/Ste and with my Falcon. On the other side I had a pc running win 95 or win 98. It is a bit slow with an St bit it works. So if you just want to save aour data onto harddisk this might be an easier possibility for you.