ZBT are fairly flexible in terms of MOQ and the 100 I've found is not set in rock.
I've made initial contact through Alibaba and ordered a couple of sample units to test initially and then placed an order of 20 each for two models which they were happy to deliver.
Yes, they are very nice for mesh nodes.
The MediaTek ones live in sweet harmony with the Atheros ones in a couple of our meshes. We use 802.11s as the 'connection' and run Batman-adv on top of that for the routing algorithm all managed centrally with a cloud controller.