Out to look at yard sales this morning, as usual for a Saturday. Nothing in the way of video game stuff of any interest, but I happened to find a WD LiveWire kit, A Powerline Ethernet bridge, each end including a 4-port switch which a cursory Google search suggested might bit gigabit. I asked how much they wanted, and it was $5AUD so I thought it was worth the gamble.
It turned out it wasn't, but I'll likely still find a use for them even though the PLE portion does not work in our house. On the way home though, I spotted a Telstra Gateway Max 2 - a rebranded Technicolor TG800VAC to be exact, which certainly does have gigabit. I seem to recall these Technicolor modems having security issues, but I'm disabling everything on it (including the wireless) and using it purely as a switch so I should be OK. After doing so and verifying it worked, I swapped it out for the fast ethernet switch that's got Duncan's desktop, Sabriena's desktop and our NAS hanging off it, and now everything but my office and behind the TV is hooked up to gigabit ethernet, and my laptop will happily do rather high speeds on Wifi on the kitchen table.