These seem to be getting harder to find – I'll see if we can locate some and put them on the Eventide Store.
The ones we use are beige plastic ones that were available from Radio Shack in the past (but not any more). They have no maker's name, and are simple 8-way Y connectors. As an alternative, you could, as you say, hardwire a branch, but you would want to keep the "stub" length short.
There are a lot on eBay (Search "RJ45 splitter") but we'll have to test some to see which are good.
