MFMulation? (Solid-state replacements for MFM drives)

Hello, all. Does anyone on the list know if anyone in our extended community has ever come up with some sort of plug-compatible flash memory replacement for MFM drives? I've a vague idea that I've seen a commercial offering at some point in the past, but obviously that'd be a fairly expensive move to make. (Fairly? Oh, OK. Very.) I've got a Northstar Horizon that I mentioned on here many, many years ago and I've just started looking at it again; once I've got it up and running it'd be nice to add some sort of permanent storage, but without jettisoning one of the floppy drives. The SuperIO board is one option, but I'd like to keep it as stock-Northstar as I can. Anyway, I'd be interested to hear any thoughts on the topic! Cheers, Simon.