I have just come across a stash of NeXT mono slabs (N1100), including mice, and monitors. The funny thing is that I only have a couple of keyboards (non-ADB). Several years back, I sold a bunch of non-ADB keyboards that I probably should have kept to match with the slabs I now have.
Prices on eBay seem to hover around $50+shipping for the slab alone (no HD). I'd like to sell mine for $60 for a slab+monitor+mouse set (no HD) plus shipping. Local pickup at Portland, OR is also okay, and is actually preferred. If you want a fully-working set (and as long as I haven't ran out of keyboards), plus your choice of NEXTSTEP or OPENSTEP installed on a SCSI drive, it'll be a flat $100+shipping for the set.
Note that shipping costs for the megapixel monitor can be expensive. I will have to purchase sturdy boxes and padding/fillings for them, or have them professionally packed at your option.
Peter