You shouldn't need most of the rest of that, either. Make sure everyone has a 2nd monitor, and you'll need to buy a $30 webcam if they don't already have laptops. I wouldn't worry about the headset, either - cell phone headsets or earpods generally work fine and most everyone has a decent one nowadays. Wait for the folks who want something nicer to ask for one.

Cheap internet is fine. I worked from home with rock bottom residential service, the cheapest they would give me, and my connectivity was fantastic, better than anything I've ever had from an office. The secret is that nobody's on the Internet from home during the day, so you've got infrastructure that was meant to handle the whole world watching Netflix at 8pm more-or-less to yourself.

This is assuming a distributed team. mind. They have a tendency to self-assemble. Partial co-location is where things get messy and you start needing to worry about smart whiteboards and fancy videoconferencing equipment and all that crap. All that's really for is to make it an eensy bit more likely that the co-located folks will be willing to collaborate with the remote folks rather than forming a clique and forgetting that the rest of the team exists.